Linear donor constructs for targeted integration

ABSTRACT

Disclosed herein are linear donor molecules comprising homology arms of 50-750 base pairs (e.g., 50-100 base pairs) flanking one or more sequences of interest. The donor molecules and/or compositions comprising these molecules can be used in methods for targeted integration of an exogenous sequence into a specified region of interest in the genome of a cell.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication No. 61/124,047, filed Apr. 14, 2008, the disclosure of whichis hereby incorporated by reference in its entirety.

STATEMENT OF RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH

Not applicable.

TECHNICAL FIELD

The present disclosure is in the field of genome engineering,particularly linear donor constructs for targeted integration into thegenome of a cell.

BACKGROUND

A major area of interest in genome biology, especially in light of thedetermination of the complete nucleotide sequences of a number ofgenomes, is the targeted integration into genomic sequences. Attemptshave been made to alter genomic sequences in cultured cells by takingadvantage of the natural phenomenon of homologous recombination. See,for example, Capecchi (1989) Science 244:1288-1292; U.S. Pat. Nos.6,528,313 and 6,528,314.

In addition, various methods and compositions for targeted cleavage ofgenomic DNA have been described. Such targeted cleavage events can beused, for example, to induce targeted mutagenesis, induce targeteddeletions of cellular DNA sequences, and facilitate targetedrecombination and targeted integration at a predetermined chromosomallocus. See, for example, United States Patent Publications 20030232410;20050208489; 20050026157; 20050064474; and 20060188987, andInternational Publication WO 2007/014275, the disclosures of which areincorporated by reference in their entireties for all purposes. Forexample, targeted integration using zinc finger nucleases has beendemonstrated with circular (plasmid) DNAs having long (˜750 base pair)homology arms. See, Moehle et al. (2007) Proc. Nat'l. Acad. Sci. USA104(9):3055-3060.

However, there remains a need for additional compositions comprisingshorter, linear exogenous polynucleotides that optionally can resistexonuclease degradation and use of these compositions in methods fortargeted integration.

SUMMARY

The present disclosure provides linear exogenous (donor) nucleic acids,compositions comprising these nucleic acids and methods of making andusing these linear donor molecules. Generally, the donor moleculesdescribed herein have two homology arms of between about 50 and 100 basepairs flanking a sequence of interest.

The donor sequences can be integrated in a targeted manner into thegenome of a cell, for example using zinc finger nucleases (ZFNs) and/ormeganucleases. Integration of the exogenous nucleic acid sequences intothe genome is facilitated by targeted double-strand cleavage of thegenome (chromosome) in the region of interest. Cleavage is preferablytargeted to the region of interest through the use of fusion proteinscomprising a zinc finger binding domain, which is engineered to bind asequence within the region of interest, and a cleavage domain or acleavage half-domain. Such cleavage stimulates integration of exogenouspolynucleotide sequences at or near the cleavage site.

In one aspect, described herein is a linear nucleic acid molecule (donormolecule) comprising homology arms of 50-100 base pairs flanking asequence of interest is provided. In certain embodiments, the lineardonor molecule stably persists in the cell into which it is introduced.In other embodiments, the linear donor molecule is modified to resistexonucleolytic cleavage, for example by placing one or morephosphorothioate phosphodiester bonds between one or more base pairs onthe ends of the donor molecule.

The sequence of interest of the donor molecule may comprise one or moresequences encoding a functional polypeptide (e.g., a cDNA), with orwithout a promoter. In certain embodiments, the nucleic acid sequencecomprises a promoterless sequence encoding an antibody, an antigen, anenzyme, a growth factor, a receptor (cell surface or nuclear), ahormone, a lymphokine, a cytokine, a reporter, functional fragments ofany of the above and combinations of the above. Expression of theintegrated sequence is then ensured by transcription driven by anendogenous promoter or other control element in the region of interest.In other embodiments, a “tandem” cassette is integrated into theselected site in this manner, the first component of the cassettecomprising a promotorless sequence as described above, followed by atranscription termination sequence, and a second sequence, encoding anautonomous expression cassette. Additional sequences (coding ornon-coding sequences) may be included in the donor molecule between thehomology arms, including but not limited to, sequences encoding a 2Apeptide, SA site, IRES, etc.

The donor molecules of the disclosure can be inserted into a specifiedlocation in a genome following cleavage of the genome, for example usingone or more fusion molecules comprising a DNA-binding domain targeted tothe specified location in the genome and a cleavage domain (e.g., a zincfinger nuclease (ZFN) or naturally or non-naturally occurringmeganuclease to a particular locus. Thus, in another aspect, providedherein is a method for integrating an exogenous sequence as describedherein into a region of interest in the genome of a cell, the methodcomprising: (a) expressing a fusion protein in the cell, the fusionprotein comprising a DNA-binding domain (e.g., zinc finger bindingdomain) and a cleavage domain or cleavage half-domain, wherein theDNA-binding domain (e.g., zinc finger binding domain) has beenengineered to bind to a target site in the region of interest in thegenome of the cell; and (b) contacting the cell with a donorpolynucleotide as described herein, wherein binding of the fusionprotein to the target site cleaves the genome of the cell in the regionof interest, thereby resulting in integration of the exogenous sequenceinto the genome of the cell within the region of interest.

In certain embodiments, the methods comprise the steps of (a) expressinga first fusion protein in the cell, the first fusion protein comprisinga first zinc finger binding domain and a first cleavage half-domain,wherein the first zinc finger binding domain has been engineered to bindto a first target site in the region of interest in the genome of thecell; (b) expressing a second fusion protein in the cell, the secondfusion protein comprising a second zinc finger binding domain and asecond cleavage half domain, wherein the second zinc finger bindingdomain binds to a second target site in the region of interest in thegenome of the cell, wherein the second target site is different from thefirst target site; and (c) contacting the cell with a exogenous donormolecule as described herein, wherein binding of the first fusionprotein to the first target site, and binding of the second fusionprotein to the second target site, positions the cleavage half-domainssuch that the genome of the cell is cleaved in the region of interest,thereby resulting in integration of the exogenous donor molecule intothe genome of the cell within the region of interest.

In any of the methods described herein, the donor polynucleotidecomprises a sequence encoding a functional polypeptide, which sequenceis inserted into the genome of the cell.

Furthermore, in any of the methods described herein, the first andsecond cleavage half-domains are from a Type IIS restrictionendonuclease, for example, FokI or StsI. Furthermore, in any of themethods described herein, at least one of the fusion proteins maycomprise an alteration in the amino acid sequence of the dimerizationinterface of the cleavage half-domain, for example such that obligateheterodimers of the cleavage half-domains are formed. Alternatively, inany of the methods described herein the cleavage domain may be anaturally or non-naturally occurring meganuclease.

In any of the methods described herein, the cell can be a mammaliancell, for example, a human, rat, mouse or rabbit cell, or a plant cell.Additionally, the cell may be derived from an insect, xenopus ornematode system. Furthermore, the cell may be arrested in the G2 phaseof the cell cycle.

The present subject matter thus includes, but is not limited to, thefollowing embodiments:

1. A linear donor nucleic acid molecule comprising homology arms ofbetween 50 and 750 base pairs and a sequence of interest, wherein thehomology arms flank the sequence of interest.

2. The linear donor nucleic acid of 1, wherein the homology arms arebetween 50 and 100 base pairs in length.

3. The linear donor nucleic acid of 1, wherein one or more of the basepairs of the homology arms are joined with a phosphorothioatephosphodiester bond.

4. The linear donor nucleic acid of 3, wherein the phosphorothioatephosphodiester bonds are positioned at the first and, optionally, secondbonds of the 5′ and 3′ ends of the donor nucleic acid.

5. The linear donor nucleic acid of any of 1 to 4, further comprising,between the homology arms, a sequence encoding a 2A peptide.

6. The linear donor nucleic acid of any of 1 through 5, furthercomprising, between the homology arms, a sequence comprising an SA site.

7. The linear donor nucleic acid of any of 1 through 6, furthercomprising, between the homology arms, a sequence comprising an IRESsequence.

8. The linear donor nucleic acid of any of 1 to 7, wherein the sequenceof interest does not encode a polypeptide.

9. The linear donor nucleic acid of any of 1 to 7, further comprising apromoter sequence operably linked to the sequence of interest.

10. The linear donor nucleic acid of any of 1 to 7 or 9, wherein thesequence of interest encodes a polypeptide.

11. The linear donor nucleic acid according to 10, wherein thepolypeptide is selected from the group consisting of an antibody, anantigen, an enzyme, a growth factor, a receptor (cell surface ornuclear), a hormone, a lymphokine, a cytokine, a reporter gene, aselectable marker, a secreted factor, an epitope tag and functionalfragments thereof and combinations thereof.

12. The linear donor nucleic acid of any of 1 to 7 or 9, wherein thesequence contains a non-coding nucleic acid.

13. The linear donor nucleic acid according to claim 12 wherein thenon-coding nucleic acid is selected from the group consisting of amiRNA, and SH-RNA, or siRNA.

14. A method for homology-dependent targeted integration of a sequenceof interest into a region of interest in the genome of the cell, themethod comprising the steps of:

(a) expressing a fusion protein in the cell, the fusion proteincomprising a DNA-binding domain and cleavage domain or a cleavagehalf-domain, wherein the DNA-binding domain has been engineered to bindto a target site in the region of interest;

(b) contacting the cell with a donor polynucleotide of any of 1 to 11,

wherein binding of the fusion protein to the target site cleaves thegenome of the cell in the region of the interest, thereby resulting inhomology-dependent targeted integration of the sequence of interest intothe genome of the cell.

15. A method for homology-dependent targeted integration of a sequenceof interest into a cell, the method comprising:

(a) expressing a first fusion protein in the cell, the first fusionprotein comprising a first DNA-binding domain and a first cleavagehalf-domain, wherein the first DNA-binding domain has been engineered tobind to a first target site in a region of interest in the genome of thecell;

(b) expressing a second fusion protein in the cell, the second fusionprotein comprising a second DNA-domain and a second cleavage halfdomain, wherein the second zinc finger binding domain binds to a secondtarget site in the region of interest in the genome of the cell, whereinthe second target site is different from the first target site; and

(c) contacting the cell with a polynucleotide comprising a donor nucleicacid according to any of 1-11;

wherein binding of the first fusion protein to the first target site,and binding of the second fusion protein to the second target site,positions the cleavage half-domains such that the genome of the cell iscleaved in the region of interest, thereby resulting inhomology-dependent integration of the donor nucleic said into the genomeof the cell.

16. The method of 14 or 15, wherein at least one DNA-binding domain is azinc finger binding domain.

17. The method of 14 to 16, wherein at least one DNA-binding domain is ameganuclease DNA-binding domain.

18. The method of 14 or 17, wherein the sequence of interest from theintegrated donor nucleic acid expresses a polypeptide.

19. The method of 14 or 17 wherein the sequence in interest from theintegrated donor comprises a non-coding nucleic acid sequence.

20. The method of 14 to 19, wherein the cleavage domain is from ameganuclease.

21. The method according to any of 14 to 19, wherein the first andsecond cleavage half-domains are from a Type IIS restrictionendonuclease.

22. The method according to 21, wherein the Type IIS restrictionendonuclease is selected from the group consisting of FokI and StsI.

23. The method according to any of 14 to 22, wherein the cell isarrested in the G2 phase of the cell cycle.

24. The method according to any of 14 to 23, wherein at least one of thefusion proteins comprises an alteration in the amino acid sequence ofthe dimerization interface of the cleavage half-domain.

25. The method according to any of 14 to 24, wherein the cell is amammalian cell.

26. The method according to 25, wherein the cell is a human cell.

27. The method according to any of 14 to 24 wherein the cell is a plantcell.

28. The method according to any of 14 to 24 wherein the cell is axenopus, insect or nematode cell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram depicting construction of a linear donorpolynucleotide as described herein. The “x” denotes phosphorothioatephosphodiester bonds as the first and second bonds on the 5′ and 3′ endsof the polynucleotide.

FIG. 2 depicts the sequence of an exemplary linear donor (SEQ ID NO: 1)having homology arms of 100 base pairs. The linear donor moleculecomprises a left homology arm from nucleotides 1 to 100 (lowercase,underlined); a splice acceptor (SA) site, from nucleotides 107 to 132(lowercase, bold); a sequence encoding a foot-in-mouth-disease virus(FMDV)-derived 2A self-processing sequence (2A peptide) from nucleotides141 to 212 (uppercase, no underlining); a sequence encoding greenfluorescent protein (GFP) poly(A) from nucleotides 219 to 1,215(uppercase, underlined); and a right homology arm from nucleotides 1235to 1334 (lowercase, underlined).

FIG. 3 depicts the sequence of an exemplary linear donor (SEQ ID NO:2)having homology arms of 75 base pairs. The linear donor moleculecomprises a left homology arm from nucleotides 1 to 75 (lowercase,underlined); an SA site from nucleotides 82 to 107 (lowercase, bold); asequence encoding a 2A peptide from nucleotides 116 to 187 (uppercase,no underlining); a sequence encoding GFP poly(A) from nucleotides 194 to1,190 (uppercase, underlined); and a right homology arm from nucleotides1210 to 1284 (lowercase, underlined).

FIG. 4 depicts the sequence of an exemplary linear donor (SEQ ID NO:3)having homology arms of 50 base pairs. The linear donor moleculecomprises a left homology arm from nucleotides 1 to 50 (lowercase,underlined); an SA site from nucleotides 57 to 82 (lowercase, bold); asequence encoding a 2A peptide from nucleotides 91 to 162 (uppercase, nounderlining); a sequence encoding GFP poly(A) from nucleotides 169 to1,165 (uppercase, underlined); and a right homology arm from nucleotides1,185 to 1,234 (lowercase, underlined).

FIG. 5 depicts the sequence of another exemplary linear donor (SEQ IDNO:4) having homology arms of 50 base pairs. The linear donor moleculecomprises a left homology arm from nucleotides 1 to 50 (lowercase,underlined); an hPGK promoter sequence from nucleotides 79 to 594(lowercase, bold); a sequence encoding GFP poly(A) from nucleotides 615to 1,611 (uppercase, underlined); and a right homology arm fromnucleotides 1,639 to 1,688 (lowercase, underlined).

FIG. 6 depicts results of a PCR assay and shows modification of thePPP1R12C (AAVS1) locus when various donor molecules as described hereinare introduced into K562 cells in the absence (lanes 2-7) or presence ofAAVS1-targeted ZFNs (lanes 8-13).

FIG. 7 is a Southern blot showing modification of the PPP1R12C (AAVS1)locus when various donor molecules as described herein are introducedinto K562 cells in the absence (lanes 3-7) or presence of AAVS1-targetedZFNs (lanes 9-13). The percent of chromosomes modified by is listedbelow lanes 9-13.

FIG. 8 depicts the percentage of GFP-positive cells as evaluated byFACS.

DETAILED DESCRIPTION

The present disclosure relates to exogenous (donor) polynucleotidesuseful for homology-dependent targeted integration (TI) into a region ofinterest in a genome. In particular, the donor polynucleotides describedherein are linear molecules comprising homology arms (HA) ofapproximately 50-100 base pairs. The homology arms flank one or moresequences of interest to be inserted into the genome of a cell. Thesedonor molecules are useful for targeted cleavage and recombination intoa specified region of interest in a genome when used in combination withfusion proteins (zinc finger nucleases) comprising a cleavage domain (ora cleavage half-domain) and a zinc finger binding domain (and/orpolynucleotides encoding these proteins). A zinc finger binding domaincan comprise one or more zinc fingers (e.g., 2, 3, 4, 5, 6, 7, 8, 9 ormore zinc fingers), and can be engineered to bind to any sequence withinthe region of interest. In the presence of ZFPs, the linear donorpolynucleotides described are integrated at high rates into the cleavagesite by homology-dependent methods.

Advantages of the linear donor molecules described herein include therapid and efficient provision of donor molecules for use with ZFNs.Currently, donor molecules used in combination with zinc fingernucleases (ZFNs) for targeted insertion into a specified locus of thegenome are plasmid constructs containing long (˜750 base pairs) homologyarms flanking a transgene of interest. Construction of such plasmiddonors is time-consuming, taking at least 2 weeks. By contrast, thelinear donor molecules described herein can be constructed within hoursand used immediately. In addition, use of linear donors as describedherein reduces or eliminates the phenomena of stable insertion of theplasmid donor into the host cell.

General

Practice of the methods, as well as preparation and use of thecompositions disclosed herein employ, unless otherwise indicated,conventional techniques in molecular biology, biochemistry, chromatinstructure and analysis, computational chemistry, cell culture,recombinant DNA and related fields as are within the skill of the art.These techniques are fully explained in the literature. See, forexample, Sambrook et al. MOLECULAR CLONING: A LABORATORY MANUAL, Secondedition, Cold Spring Harbor Laboratory Press, 1989 and Third edition,2001; Ausubel et al., CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley& Sons, New York, 1987 and periodic updates; the series METHODS INENZYMOLOGY, Academic Press, San Diego; Wolffe, CHROMATIN STRUCTURE ANDFUNCTION, Third edition, Academic Press, San Diego, 1998; METHODS INENZYMOLOGY, Vol. 304, “Chromatin” (P. M. Wassarman and A. P. Wolffe,eds.), Academic Press, San Diego, 1999; and METHODS IN MOLECULARBIOLOGY, Vol. 119, “Chromatin Protocols” (P. B. Becker, ed.) HumanaPress, Totowa, 1999.

DEFINITIONS

The terms “nucleic acid,” “polynucleotide,” and “oligonucleotide” areused interchangeably and refer to a deoxyribonucleotide orribonucleotide polymer, in linear or circular conformation, and ineither single- or double-stranded form. For the purposes of the presentdisclosure, these terms are not to be construed as limiting with respectto the length of a polymer. The terms can encompass known analogues ofnatural nucleotides, as well as nucleotides that are modified in thebase, sugar and/or phosphate moieties (e.g., phosphorothioatebackbones). In general, an analogue of a particular nucleotide has thesame base-pairing specificity; i.e., an analogue of A will base-pairwith T.

The terms “polypeptide,” “peptide” and “protein” are usedinterchangeably to refer to a polymer of amino acid residues. The termalso applies to amino acid polymers in which one or more amino acids arechemical analogues or modified derivatives of a correspondingnaturally-occurring amino acids.

“Binding” refers to a sequence-specific, non-covalent interactionbetween macromolecules (e.g., between a protein and a nucleic acid). Notall components of a binding interaction need be sequence-specific (e.g.,contacts with phosphate residues in a DNA backbone), as long as theinteraction as a whole is sequence-specific. Such interactions aregenerally characterized by a dissociation constant (K_(d)) of 10⁻⁶ M⁻¹or lower. “Affinity” refers to the strength of binding: increasedbinding affinity being correlated with a lower K_(d).

A “binding protein” is a protein that is able to bind non-covalently toanother molecule. A binding protein can bind to, for example, a DNAmolecule (a DNA-binding protein), an RNA molecule (an RNA-bindingprotein) and/or a protein molecule (a protein-binding protein). In thecase of a protein-binding protein, it can bind to itself (to formhomodimers, homotrimers, etc.) and/or it can bind to one or moremolecules of a different protein or proteins. A binding protein can havemore than one type of binding activity. For example, zinc fingerproteins have DNA-binding, RNA-binding and protein-binding activity.

A “zinc finger DNA binding protein” (or binding domain) is a protein, ora domain within a larger protein, that binds, DNA in a sequence-specificmanner through one or more zinc fingers, which are regions of amino acidsequence within the binding domain whose structure is stabilized throughcoordination of a zinc ion. The term zinc finger DNA binding protein isoften abbreviated as zinc finger protein or ZFP.

Zinc finger binding domains can be “engineered” to bind to apredetermined nucleotide sequence. Non-limiting examples of methods forengineering zinc finger proteins are design and selection. A designedzinc finger protein is a protein not occurring in nature whosedesign/composition results principally from rational criteria. Rationalcriteria for design include application of substitution rules andcomputerized algorithms for processing information in a database storinginformation of existing ZFP designs and binding data. See, for example,U.S. Pat. Nos. 6,140,081; 6,453,242; and 6,534,261; see, also WO98/53058; WO 98/53059; WO 98/53060; WO 02/016536 and WO 03/016496.

A “selected” zinc finger protein is a protein not found in nature whoseproduction results primarily from an empirical process such as phagedisplay, interaction trap or hybrid selection. See e.g., U.S. Pat. No.5,789,538; U.S. Pat. No. 5,925,523; U.S. Pat. No. 6,007,988; U.S. Pat.No. 6,013,453; U.S. Pat. No. 6,200,759; WO 95/19431; WO 96/06166; WO98/53057; WO 98/54311; WO 00/27878; WO 01/60970 WO 01/88197 and WO02/099084.

The term “sequence” refers to a nucleotide sequence of any length, whichcan be DNA or RNA; can be linear, circular or branched and can be eithersingle-stranded or double stranded. The term “donor sequence” refers toa nucleotide sequence that is inserted into a genome. A donor sequencecan be of any length, for example between 2 and 10,000 nucleotides inlength (or any integer value therebetween or thereabove), preferablybetween about 100 and 1,000 nucleotides in length (or any integertherebetween), more preferably between about 200 and 500 nucleotides inlength.

A “homologous, non-identical sequence” refers to a first sequence whichshares a degree of sequence identity with a second sequence, but whosesequence is not identical to that of the second sequence. For example, apolynucleotide comprising the wild-type sequence of a mutant gene ishomologous and non-identical to the sequence of the mutant gene. Incertain embodiments, the degree of homology between the two sequences issufficient to allow homologous recombination therebetween, utilizingnormal cellular mechanisms. Two homologous non-identical sequences canbe any length and their degree of non-homology can be as small as asingle nucleotide (e.g., for correction of a genomic point mutation bytargeted homologous recombination) or as large as 10 or more kilobases(e.g., for insertion of a gene at a predetermined ectopic site in achromosome). Two polynucleotides comprising the homologous non-identicalsequences need not be the same length. For example, an exogenouspolynucleotide (i.e., donor polynucleotide) of between 20 and 10,000nucleotides or nucleotide pairs can be used.

Techniques for determining nucleic acid and amino acid sequence identityare known in the art. Typically, such techniques include determining thenucleotide sequence of the mRNA for a gene and/or determining the aminoacid sequence encoded thereby, and comparing these sequences to a secondnucleotide or amino acid sequence. Genomic sequences can also bedetermined and compared in this fashion. In general, identity refers toan exact nucleotide-to-nucleotide or amino acid-to-amino acidcorrespondence of two polynucleotides or polypeptide sequences,respectively. Two or more sequences (polynucleotide or amino acid) canbe compared by determining their percent identity. The percent identityof two sequences, whether nucleic acid or amino acid sequences, is thenumber of exact matches between two aligned sequences divided by thelength of the shorter sequences and multiplied by 100. An approximatealignment for nucleic acid sequences is provided by the local homologyalgorithm of Smith and Waterman, Advances in Applied Mathematics2:482-489 (1981). This algorithm can be applied to amino acid sequencesby using the scoring matrix developed by Dayhoff, Atlas of ProteinSequences and Structure, M. O. Dayhoff ed., 5 suppl. 3:353-358, NationalBiomedical Research Foundation, Washington, D.C., USA, and normalized byGribskov, Nucl. Acids Res. 14(6):6745-6763 (1986). An exemplaryimplementation of this algorithm to determine percent identity of asequence is provided by the Genetics Computer Group (Madison, Wis.) inthe “BestFit” utility application. The default parameters for thismethod are described in the Wisconsin Sequence Analysis Package ProgramManual, Version 8 (1995) (available from Genetics Computer Group,Madison, Wis.). A preferred method of establishing percent identity inthe context of the present disclosure is to use the MPSRCH package ofprograms copyrighted by the University of Edinburgh, developed by JohnF. Collins and Shane S. Sturrok, and distributed by IntelliGenetics,Inc. (Mountain View, Calif.). From this suite of packages theSmith-Waterman algorithm can be employed where default parameters areused for the scoring table (for example, gap open penalty of 12, gapextension penalty of one, and a gap of six). From the data generated the“Match” value reflects sequence identity. Other suitable programs forcalculating the percent identity or similarity between sequences aregenerally known in the art, for example, another alignment program isBLAST, used with default parameters. For example, BLASTN and BLASTP canbe used using the following default parameters: genetic code=standard;filter=none; strand=both; cutoff 60; expect=10; Matrix=BLOSUM62;Descriptions=50 sequences; sort by=HIGH SCORE; Databases=non-redundant,GenBank+EMBL+DDBJ+PDB+GenBank CDS translations+Swissprotein+Spupdate+PIR. Details of these programs can be found on theinternet. With respect to sequences described herein, the range ofdesired degrees of sequence identity is approximately 80% to 100% andany integer value therebetween. Typically the percent identities betweensequences are at least 70-75%, preferably 80-82%, more preferably85-90%, even more preferably 92%, still more preferably 95%, and mostpreferably 98% sequence identity.

Alternatively, the degree of sequence similarity between polynucleotidescan be determined by hybridization of polynucleotides under conditionsthat allow formation of stable duplexes between homologous regions,followed by digestion with single-stranded-specific nuclease(s), andsize determination of the digested fragments. Two nucleic acid, or twopolypeptide sequences are substantially homologous to each other whenthe sequences exhibit at least about 70%-75%, preferably 80%-82%, morepreferably 85%-90%, even more preferably 92%, still more preferably 95%,and most preferably 98% sequence identity over a defined length of themolecules, as determined using the methods above. As used herein,substantially homologous also refers to sequences showing completeidentity to a specified DNA or polypeptide sequence. DNA sequences thatare substantially homologous can be identified in a Southernhybridization experiment under, for example, stringent conditions, asdefined for that particular system. Defining appropriate hybridizationconditions is within the skill of the art. See, e.g., Sambrook et al.,supra; Nucleic Acid Hybridization: A Practical Approach, editors B. D.Hames and S. J. Higgins, (1985) Oxford; Washington, D.C.; IRL Press).

Selective hybridization of two nucleic acid fragments can be determinedas follows. The degree of sequence identity between two nucleic acidmolecules affects the efficiency and strength of hybridization eventsbetween such molecules. A partially identical nucleic acid sequence willat least partially inhibit the hybridization of a completely identicalsequence to a target molecule. Inhibition of hybridization of thecompletely identical sequence can be assessed using hybridization assaysthat are well known in the art (e.g., Southern (DNA) blot, Northern(RNA) blot, solution hybridization, or the like, see Sambrook, et al.,Molecular Cloning: A Laboratory Manual, Second Edition, (1989) ColdSpring Harbor, N.Y.). Such assays can be conducted using varying degreesof selectivity, for example, using conditions varying from low to highstringency. If conditions of low stringency are employed, the absence ofnon-specific binding can be assessed using a secondary probe that lackseven a partial degree of sequence identity (for example, a probe havingless than about 30% sequence identity with the target molecule), suchthat, in the absence of non-specific binding events, the secondary probewill not hybridize to the target.

When utilizing a hybridization-based detection system, a nucleic acidprobe is chosen that is complementary to a reference nucleic acidsequence, and then by selection of appropriate conditions the probe andthe reference sequence selectively hybridize, or bind, to each other toform a duplex molecule. A nucleic acid molecule that is capable ofhybridizing selectively to a reference sequence under moderatelystringent hybridization conditions typically hybridizes under conditionsthat allow detection of a target nucleic acid sequence of at least about10-14 nucleotides in length having at least approximately 70% sequenceidentity with the sequence of the selected nucleic acid probe. Stringenthybridization conditions typically allow detection of target nucleicacid sequences of at least about 10-14 nucleotides in length having asequence identity of greater than about 90-95% with the sequence of theselected nucleic acid probe. Hybridization conditions useful forprobe/reference sequence hybridization, where the probe and referencesequence have a specific degree of sequence identity, can be determinedas is known in the art (see, for example, Nucleic Acid Hybridization: APractical Approach, editors B. D. Hames and S. J. Higgins, (1985)Oxford; Washington, D.C.; IRL Press).

Conditions for hybridization are well-known to those of skill in theart. Hybridization stringency refers to the degree to whichhybridization conditions disfavor the formation of hybrids containingmismatched nucleotides, with higher stringency correlated with a lowertolerance for mismatched hybrids. Factors that affect the stringency ofhybridization are well-known to those of skill in the art and include,but are not limited to, temperature, pH, ionic strength, andconcentration of organic solvents such as, for example, formamide anddimethylsulfoxide. As is known to those of skill in the art,hybridization stringency is increased by higher temperatures, lowerionic strength and lower solvent concentrations.

With respect to stringency conditions for hybridization, it is wellknown in the art that numerous equivalent conditions can be employed toestablish a particular stringency by varying, for example, the followingfactors: the length and nature of the sequences, base composition of thevarious sequences, concentrations of salts and other hybridizationsolution components, the presence or absence of blocking agents in thehybridization solutions (e.g., dextran sulfate, and polyethyleneglycol), hybridization reaction temperature and time parameters, as wellas, varying wash conditions. The selection of a particular set ofhybridization conditions is selected following standard methods in theart (see, for example, Sambrook, et al., Molecular Cloning: A LaboratoryManual, Second Edition, (1989) Cold Spring Harbor, N.Y.).

“Recombination” refers to a process of exchange of genetic informationbetween two polynucleotides. For the purposes of this disclosure,“homologous recombination (HR)” refers to the specialized form of suchexchange that takes place, for example, during repair of double-strandbreaks in cells. This process requires nucleotide sequence homology,uses a “donor” molecule to template repair of a “target” molecule (i.e.,the one that experienced the double-strand break), and is variouslyknown as “non-crossover gene conversion” or “short tract geneconversion,” because it leads to the transfer of genetic informationfrom the donor to the target. Without wishing to be bound by anyparticular theory, such transfer can involve mismatch correction ofheteroduplex DNA that forms between the broken target and the donor,and/or “synthesis-dependent strand annealing,” in which the donor isused to resynthesize genetic information that will become part of thetarget, and/or related processes. Such specialized HR often results inan alteration of the sequence of the target molecule such that part orall of the sequence of the donor polynucleotide is incorporated into thetarget polynucleotide.

“Cleavage” refers to the breakage of the covalent backbone of a DNAmolecule. Cleavage can be initiated by a variety of methods including,but not limited to, enzymatic or chemical hydrolysis of a phosphodiesterbond. Both single-stranded cleavage and double-stranded cleavage arepossible, and double-stranded cleavage can occur as a result of twodistinct single-stranded cleavage events. DNA cleavage can result in theproduction of either blunt ends or staggered ends. In certainembodiments, fusion polypeptides are used for targeted double-strandedDNA cleavage.

A “cleavage domain” comprises one or more polypeptide sequences whichpossesses catalytic activity for DNA cleavage. A cleavage domain can becontained in a single polypeptide chain or cleavage activity can resultfrom the association of two (or more) polypeptides.

A “cleavage half-domain” is a polypeptide sequence which, in conjunctionwith a second polypeptide (either identical or different) forms acomplex having cleavage activity (preferably double-strand cleavageactivity).

“Chromatin” is the nucleoprotein structure comprising the cellulargenome. Cellular chromatin comprises nucleic acid, primarily DNA, andprotein, including histones and non-histone chromosomal proteins. Themajority of eukaryotic cellular chromatin exists in the form ofnucleosomes, wherein a nucleosome core comprises approximately 150 basepairs of DNA associated with an octamer comprising two each of histonesH2A, H2B, H3 and H4; and linker DNA (of variable length depending on theorganism) extends between nucleosome cores. A molecule of histone H1 isgenerally associated with the linker DNA. For the purposes of thepresent disclosure, the term “chromatin” is meant to encompass all typesof cellular nucleoprotein, both prokaryotic and eukaryotic. Cellularchromatin includes both chromosomal and episomal chromatin.

A “chromosome,” is a chromatin complex comprising all or a portion ofthe genome of a cell. The genome of a cell is often characterized by itskaryotype, which is the collection of all the chromosomes that comprisethe genome of the cell. The genome of a cell can comprise one or morechromosomes.

An “episome” is a replicating nucleic acid, nucleoprotein complex orother structure comprising a nucleic acid that is not part of thechromosomal karyotype of a cell. Examples of episomes include plasmidsand certain viral genomes.

An “accessible region” is a site in cellular chromatin in which a targetsite present in the nucleic acid can be bound by an exogenous moleculewhich recognizes the target site. Without wishing to be bound by anyparticular theory, it is believed that an accessible region is one thatis not packaged into a nucleosomal structure. The distinct structure ofan accessible region can often be detected by its sensitivity tochemical and enzymatic probes, for example, nucleases.

A “target site” or “target sequence” is a nucleic acid sequence thatdefines a portion of a nucleic acid to which a binding molecule willbind, provided sufficient conditions for binding exist. For example, thesequence 5′-GAATTC-3′ is a target site for the Eco RI restrictionendonuclease.

An “exogenous” molecule is a molecule that is not normally present in acell, but can be introduced into a cell by one or more genetic,biochemical or other methods. “Normal presence in the cell” isdetermined with respect to the particular developmental stage andenvironmental conditions of the cell. Thus, for example, a molecule thatis present only during embryonic development of muscle is an exogenousmolecule with respect to an adult muscle cell. Similarly, a moleculeinduced by heat shock is an exogenous molecule with respect to anon-heat-shocked cell. An exogenous molecule can comprise, for example,a coding sequence for any polypeptide or fragment thereof, a functioningversion of a malfunctioning endogenous molecule or a malfunctioningversion of a normally-functioning endogenous molecule. An exogenousmolecule can also be the same type of molecule as an endogenous moleculebut be derived from a different species than the species the endogenousmolecule is derived from. For example, a human nucleic acid sequence maybe introduced into a cell line originating from a hamster or mouse.

An exogenbus molecule can be, among other things, a small molecule, suchas is generated by a combinatorial chemistry process, or a macromoleculesuch as a protein, nucleic acid, carbohydrate, lipid, glycoprotein,lipoprotein, polysaccharide, any modified derivative of the abovemolecules, or any complex comprising one or more of the above molecules.Nucleic acids include DNA and RNA, can be single- or double-stranded;can be linear, branched or circular; and can be of any length. Nucleicacids include those capable of forming duplexes, as well astriplex-forming nucleic acids. See, for example, U.S. Pat. Nos.5,176,996 and 5,422,251. Exogenous nucleic acid molecules that can betargeted for insertion into a genome are also referred to as “donor”polynucleotides. Proteins include, but are not limited to, DNA-bindingproteins, transcription factors, chromatin remodeling factors,methylated DNA binding proteins, polymerases, methylases, demethylases,acetylases, deacetylases, kinases, phosphatases, integrases,recombinases, ligases, topoisomerases, gyrases and helicases.

An exogenous molecule can be the same type of molecule as an endogenousmolecule, e.g., an exogenous protein or nucleic acid. For example, anexogenous nucleic acid can comprise an infecting viral genome, a plasmidor episome introduced into a cell, or a chromosome that is not normallypresent in the cell. Methods for the introduction of exogenous moleculesinto cells are known to those of skill in the art and include, but arenot limited to, lipid-mediated transfer (i.e., liposomes, includingneutral and cationic lipids), electroporation, direct injection, cellfusion, particle bombardment, calcium phosphate co-precipitation,DEAE-dextran-mediated transfer and viral vector-mediated transfer.

By contrast, an “endogenous” molecule is one that is normally present ina particular cell at a particular developmental stage under particularenvironmental conditions. For example, an endogenous nucleic acid cancomprise a chromosome, the genome of a mitochondrion, chloroplast orother organelle, or a naturally-occurring episomal nucleic acid.Additional endogenous molecules can include proteins, for example,transcription factors and enzymes.

A “fusion” molecule is a molecule in which two or more subunit moleculesare linked, preferably covalently. The subunit molecules can be the samechemical type of molecule, or can be different chemical types ofmolecules. Examples of the first type of fusion molecule include, butare not limited to, fusion proteins (for example, a fusion between a ZFPDNA-binding domain and a cleavage domain) and fusion nucleic acids (forexample, a nucleic acid encoding the fusion protein described supra).Examples of the second type of fusion molecule include, but are notlimited to, a fusion between a triplex-forming nucleic acid and apolypeptide, and a fusion between a minor groove binder and a nucleicacid.

Expression of a fusion protein in a cell can result from delivery of thefusion protein to the cell or by delivery of a polynucleotide encodingthe fusion protein to a cell, wherein the polynucleotide is transcribed,and the transcript is translated, to generate the fusion protein.Trans-splicing, polypeptide cleavage and polypeptide ligation can alsobe involved in expression of a protein in a cell. Methods forpolynucleotide and polypeptide delivery to cells are presented elsewherein this disclosure.

A “gene,” for the purposes of the present disclosure, includes a DNAregion encoding a gene product (see infra), as well as all DNA regionswhich regulate the production of the gene product, whether or not suchregulatory sequences are adjacent to coding and/or transcribedsequences. Accordingly, a gene includes, but is not necessarily limitedto, promoter sequences, terminators, translational regulatory sequencessuch as ribosome binding sites and internal ribosome entry sites,enhancers, silencers, insulators, boundary elements, replicationorigins, matrix attachment sites and locus control regions.

“Gene expression” refers to the conversion of the information, containedin a gene, into a gene product. A gene product can be the directtranscriptional product of a gene (e.g., mRNA, tRNA, rRNA, antisenseRNA, ribozyme, structural RNA or any other type of RNA) or a proteinproduced by translation of a mRNA. Gene products also include RNAs whichare modified, by processes such as capping, polyadenylation,methylation, and editing, and proteins modified by, for example,methylation, acetylation, phosphorylation, ubiquitination,ADP-ribosylation, myristilation, and glycosylation.

“Modulation” of gene expression refers to a change in the activity of agene. Modulation of expression can include, but is not limited to, geneactivation and gene repression.

“Eukaryotic” cells include, but are not limited to, fungal cells (suchas yeast), plant cells, animal cells, mammalian cells and human cells.

“Plant” cells include, but are not limited to, cells of monocotyledonous(monocots) or dicotyledonous (dicots) plants. Non-limiting examples ofmonocots include cereal plants such as maize, rice, barley, oats, wheat,sorghum, rye, sugarcane, pineapple, onion, banana, and coconut.Non-limiting examples of dicots include tobacco, tomato, sunflower,cotton, sugarbeet, potato, lettuce, melon, soybean, canola (rapeseed),and alfalfa. Plant cells may be from any part of the plant and/or fromany stage of plant development.

A “region of interest” is any region of cellular chromatin, such as, forexample, a gene or a non-coding sequence within or adjacent to a gene,in which it is desirable to bind an exogenous molecule. Binding can befor the purposes of targeted DNA cleavage and/or targeted recombination.A region of interest can be present in a chromosome, an episome, anorganellar genome (e.g., mitochondrial, chloroplast), or an infectingviral genome, for example. A region of interest can be within the codingregion of a gene, within transcribed non-coding regions such as, forexample, leader sequences, trailer sequences or introns, or withinnon-transcribed-regions, either upstream or downstream of the codingregion. A region of interest can be as small as a single nucleotide pairor up to 2,000 nucleotide pairs in length, or any integral value ofnucleotide pairs.

The terms “operative linkage” and “operatively linked” (or “operablylinked”) are used interchangeably with reference to a juxtaposition oftwo or more components (such as sequence elements), in which thecomponents are arranged such that both components function normally andallow the possibility that at least one of the components can mediate afunction that is exerted upon at least one of the other components. Byway of illustration, a transcriptional regulatory sequence, such as apromoter, is operatively linked to a coding sequence if thetranscriptional regulatory sequence controls the level of transcriptionof the coding sequence in response to the presence or absence of one ormore transcriptional regulatory factors. A transcriptional regulatorysequence is generally operatively linked in cis with a coding sequence,but need not be directly adjacent to it. For example, an enhancer is atranscriptional regulatory sequence that is operatively linked to acoding sequence, even though they are not contiguous.

With respect to fusion polypeptides, the term “operatively linked” canrefer to the fact that each of the components performs the same functionin linkage to the other component as it would if it were not so linked.For example, with respect to a fusion polypeptide in which a ZFPDNA-binding domain is fused to a cleavage domain, the ZFP DNA-bindingdomain and the cleavage domain are in operative linkage if, in thefusion polypeptide, the ZFP DNA-binding domain portion is able to bindits target site and/or its binding site, while the cleavage domain isable to cleave DNA in the vicinity of the target site.

A “functional fragment” of a protein, polypeptide or nucleic acid is aprotein, polypeptide or nucleic acid whose sequence is not identical tothe full-length protein, polypeptide or nucleic acid, yet retains thesame function as the full-length protein, polypeptide or nucleic acid. Afunctional fragment can possess more, fewer, or the same number ofresidues as the corresponding native molecule, and/or can contain one ormore amino acid or nucleotide substitutions. Methods for determining thefunction of a nucleic acid (e.g., coding function, ability to hybridizeto another nucleic acid) are well-known in the art. Similarly, methodsfor determining protein function are well-known. For example, theDNA-binding function of a polypeptide can be determined, for example, byfilter-binding, electrophoretic mobility-shift, or immunoprecipitationassays. DNA cleavage can be assayed by gel electrophoresis. See Ausubelet al., supra. The ability of a protein to interact with another proteincan be determined, for example, by co-immunoprecipitation, two-hybridassays or complementation, both genetic and biochemical. See, forexample, Fields et al. (1989) Nature 340:245-246; U.S. Pat. No.5,585,245 and PCT WO 98/44350.

Exogenous (Donor) Polynucleotides

Described herein are polynucleotides for insertion into the genome, alsoreferred to as “exogenous” polynucleotides or “donor” polynucleotides.It has been shown that plasmid donors carrying 750 bp homology armsflanking a transgene of interest, in combination with designed zincfinger nucleases (ZFNs) can be used for targeted gene alteration. See,e.g., Moehle et al. (2007) Proc. Nat'l. Acad. Sci. USA 104(9):3055-3060and U.S. Patent Publication No. 20050064474. Constructing such plasmiddonor polynucleotides with long homology arms is a time-consumingprocedure, involving: design PCR primers that amplify an ˜1.5 kbfragment of the locus of interest; identification (by amplification,cloning and sequencing) of a single clone carrying the desired fragmentand lacking PCR-induced mutations; introduction (typically bysite-directed mutagenesis) of a unique RFLP into the center of thatfragment; cloning of the ORF of interest into that fragment;identification (typically by restriction digest) of a clone carrying theORF in the desired orientation; and amplification of the plasmid tosufficient quantities for use in targeted genomic alteration. Under thebest circumstances, this process takes approximately two weeks andresults in a circular (plasmid) donor polynucleotide.

Surprisingly, we demonstrate herein that linear donor sequences of thedisclosure comprising short homology arms of approximately 50-100 basepairs can be effectively integrated into the genome of cell. The lineardonor sequences described herein take only hours to construct.

In certain embodiments, the linear donor sequences described herein are25 to 50 base pairs in length (or any value therebetween, including 26,27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44,45, 46, 47, 48, 49 or 50 nucleotides). In other embodiments, thesequences are between 50 and 75 nucleotides in length (including 50, 51,52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69,70, 71, 72, 73, 74 or 75 nucleotides in length). In still otherembodiments, the sequences are between 75 and 100 nucleotides in length(including 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89,90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100 nucleotides in length).In still other embodiments, the donor polynucleotides are between 100and 150 nucleotides in length (or any value therebetween). In otherembodiments, the donor polynucleotides are between 50 and 750nucleotides in length (e.g., 50 and 100, 50 and 150, 50 and 200, 50 and250, 50 and 300, 50 and 350, 50 and 400, 50 and 450, 50 and 500, 50 and550, 50 and 600, 50 and 650, 50 and 700).

The donor sequences described herein may be isolated from plasmids,cells or other sources using standard techniques known in the art suchas PCR. Alternatively, they may be chemically synthesized using standardoligonucleotide synthesis techniques. Typically, the donorpolynucleotides are made by PCR using a primer with a 50-100 bp 5′portion homologous to the genomic target, and a 15-18 bp portionidentical to the ORF of interest (FIG. 1).

The linear donor polynucleotides described herein may include one ormore phosphorothioate phosphodiester bonds between terminal base pairsto protect the linear donor polynucleotide from exonucleolyticdegradation. These bonds may be in two or more positions at the 5′and/or 3′ ends of the molecule and may be added during isolation orsynthesis using standard methodology. See, e.g., Ciafre et al. (1995)Nucleic Acids Res. 23(20):4134-42; Johansson et al. (2002) Vaccine20(27-28):3379-88. In embodiments in which the donor polynucleotide isisolated by PCR using primers (FIG. 1), the 5′ ends of the primer (anddonor polynucleotide) are typically phosphorothioate phosphodiesterbonds. Alternatively, the linear donor polynucleotides may include oneor more 5′ deoxynucleotides, biotin and/one or more amine groups, all ofwhich have been shown to reduce exonucleolytic degradation.

The exogenous (donor) polynucleotide may comprise any sequence ofinterest (exogenous sequence). Exemplary exogenous sequences include,but are not limited to any polypeptide coding sequence (e.g., cDNAs),promoter sequences, enhancer sequences, epitope tags, marker genes,cleavage enzyme recognition sites, epitope tags and various types ofexpression constructs. Marker genes include, but are not limited to,sequences encoding proteins that mediate antibiotic resistance (e.g.,ampicillin resistance, neomycin resistance, G418 resistance, puromycinresistance), sequences encoding colored or fluorescent or luminescentproteins (e.g., green fluorescent protein, enhanced green fluorescentprotein, red fluorescent protein, luciferase), and proteins whichmediate enhanced cell growth and/or gene amplification (e.g.,dihydrofolate reductase). Epitope tags include, for example, one or morecopies of FLAG, His, myc, Tap, HA or any detectable amino acid sequence.

The exogenous (donor) polynucleotide may also comprise sequences whichdo not encode polypeptides but rather any type of noncoding sequence, aswell as one or more control elements (e.g., promoters). In addition, theexogenous nucleic acid sequence may produce one or more RNA molecules(e.g., small hairpin RNAs (shRNAs), inhibitory RNAs (RNAis), microRNAs(miRNAs), etc.).

A donor molecule can contain several, discontinuous regions of homologyto cellular chromatin. For example, the regions of homology can flanktwo or more regions containing the desired alterations. In a preferredembodiment, the exogenous sequence comprises a polynucleotide encodingany polypeptide of which expression in the cell is desired, including,but not limited to antibodies, antigens, enzymes, receptors (cellsurface or nuclear), hormones, lymphokines, cytokines, reporterpolypeptides, growth factors, and functional fragments of any of theabove. The coding sequences may be, for example, cDNAs.

A donor molecule can be a linear molecule following linearization, as aresult of ZFN directed cleavage, of a plasmid taken up by a cell. Inanother embodiment, the linear donor molecule can reside in the genomeof the cell wherein the donor molecule becomes available for homologydirected targeted integration following ZFN directed cleavage andrelease of the donor from the genome.

For example, the exogenous sequence may comprise a sequence encoding apolypeptide that is lacking or non-functional in the subject having agenetic disease, including but not limited to any of the followinggenetic diseases: achondroplasia, achromatopsia, acid maltasedeficiency, adenosine deaminase deficiency (OMIM No. 102700),adrenoleukodystrophy, aicardi syndrome, alpha-1 antitrypsin deficiency,alpha-thalassemia, androgen insensitivity syndrome, apert syndrome,arrhythmogenic right ventricular, dysplasia, ataxia telangictasia, barthsyndrome, beta-thalassemia, blue rubber bleb nevus syndrome, canavandisease, chronic granulomatous diseases (CGD), cri du chat syndrome,cystic fibrosis, dercum's disease, ectodermal dysplasia, fanconi anemia,fibrodysplasia ossificans progressive, fragile X syndrome, galactosemis,Gaucher's disease, generalized gangliosidoses (e.g., GM1),hemochromatosis, the hemoglobin C mutation in the 6^(th) codon ofbeta-globin (HbC), hemophilia, Huntington's disease, Hurler Syndrome,hypophosphatasia, Klinefleter syndrome, Krabbes Disease, Langer-GiedionSyndrome, leukocyte adhesion deficiency (LAD, OMIM No. 116920),leukodystrophy, long QT syndrome, Marfan syndrome, Moebius syndrome,mucopolysaccharidosis (MPS), nail patella syndrome, nephrogenic diabetesinsipdius, neurofibromatosis, Neimann-Pick disease, osteogenesisimperfecta, porphyria, Prader-Willi syndrome, progeria, Proteussyndrome, retinoblastoma, Rett syndrome, Rubinstein-Taybi syndrome,Sanfilippo syndrome, severe combined immunodeficiency (SCID), Shwachmansyndrome, sickle cell disease (sickle cell anemia), Smith-Magenissyndrome, Stickler syndrome, Tay-Sachs disease, Thrombocytopenia AbsentRadius (TAR) syndrome, Treacher Collins syndrome, trisomy, tuberoussclerosis, Turner's syndrome, urea cycle disorder, von Hippel-Landaudisease, Waardenburg syndrome, Williams syndrome, Wilson's disease,Wiskott-Aldrich syndrome, X-linked lymphoproliferative syndrome (XLP,OMIM No. 308240).

Additional exemplary diseases that can be treated by targetedintegration include acquired immunodeficiencies, lysosomal storagediseases (e.g., Gaucher's disease, GM1, Fabry disease and Tay-Sachsdisease), mucopolysaccahidosis (e.g. Hunter's disease, Hurler'sdisease), hemoglobinopathies (e.g., sickle cell diseases, HbC,α-thalassemia, β-thalassemia) and hemophilias.

In certain embodiments, the exogenous sequences can comprise a markergene (described above), allowing selection of cells that have undergonetargeted integration, and a linked sequence encoding an additionalfunctionality. Non-limiting examples of marker genes include GFP, drugselection marker(s) and the like.

Furthermore, although not required for expression, exogenous sequencesmay also transcriptional or translational regulatory sequences, forexample, promoters, enhancers, insulators, internal ribosome entrysites, sequences encoding 2A peptides and/or polyadenylation signals.

Target Sites

The disclosed methods and compositions include fusion proteinscomprising a cleavage domain (or a cleavage half-domain) and a zincfinger domain, in which the zinc finger domain, by binding to a sequencea region of interest in the genome of a cell directs the activity of thecleavage domain (or cleavage half-domain) to the vicinity of thesequence and, hence, induces cleavage (e.g., a double stranded break) inthe region of interest. As set forth elsewhere in this disclosure, azinc finger domain can be engineered to bind to virtually any desiredsequence. Accordingly, one or more zinc finger binding domains can beengineered to bind to one or more sequences in the region of interest.Expression of a fusion protein comprising a zinc finger binding domainand a cleavage domain (or of two fusion proteins, each comprising a zincfinger binding domain and a cleavage half-domain), in a cell, effectscleavage in the region of interest.

Selection of a sequence in a region of interest for binding by a zincfinger domain (e.g., a target site) can be accomplished, for example,according to the methods disclosed in co-owned U.S. Pat. No. 6,453,242(Sep. 17, 2002), which also discloses methods for designing ZFPs to bindto a selected sequence. It will be clear to those skilled in the artthat simple visual inspection of a nucleotide sequence can also be usedfor selection of a target site. Accordingly, any means for target siteselection can be used in the methods described herein.

Target sites are generally composed of a plurality of adjacent targetsubsites. A target subsite refers to the sequence (usually either anucleotide triplet, or a nucleotide quadruplet that can overlap by onenucleotide with an adjacent quadruplet) bound by an individual zincfinger. See, for example, WO 02/077227. If the strand with which a zincfinger protein makes most contacts is designated the target strand“primary recognition strand,” or “primary contact strand,” some zincfinger proteins bind to a three base triplet in the target strand and afourth base on the non-target strand. A target site generally has alength of at least 9 nucleotides and, accordingly, is bound by a zincfinger binding domain comprising at least three zinc fingers. Howeverbinding of, for example, a 4-finger binding domain to a 12-nucleotidetarget site, a 5-finger binding domain to a 15-nucleotide target site ora 6-finger binding domain to an 18-nucleotide target site, is alsopossible. As will be apparent, binding of larger binding domains (e.g.,7-, 8-, 9-finger and more) to longer target sites is also possible.

It is not necessary for a target site to be a multiple of threenucleotides. For example, in cases in which cross-strand interactionsoccur (see, e.g., U.S. Pat. No. 6,453,242 and WO 02/077227), one or moreof the individual zinc fingers of a multi-finger binding domain can bindto overlapping quadruplet subsites. As a result, a three-finger proteincan bind a 10-nucleotide sequence, wherein the tenth nucleotide is partof a quadruplet bound by a terminal finger, a four-finger protein canbind a 13-nucleotide sequence, wherein the thirteenth nucleotide is partof a quadruplet bound by a terminal finger, etc.

The length and nature of amino acid linker sequences between individualzinc fingers in a multi-finger binding domain also affects binding to atarget sequence. For example, the presence of a so-called “non-canonicallinker,” “long linker” or “structured linker” between adjacent zincfingers in a multi-finger binding domain can allow those fingers to bindsubsites which are not immediately adjacent. Non-limiting examples ofsuch linkers are described, for example, in U.S. Pat. No. 6,479,626 andWO 01/53480. Accordingly, one or more subsites, in a target site for azinc finger binding domain, can be separated from each other by 1, 2, 3,4, 5 or more nucleotides. To provide but one example, a four-fingerbinding domain can bind to a 13-nucleotide target site comprising, insequence, two contiguous 3-nucleotide subsites, an interveningnucleotide, and two contiguous triplet subsites.

Distance between sequences (e.g., target sites) refers to the number ofnucleotides or nucleotide pairs intervening between two sequences, asmeasured from the edges of the sequences nearest each other.

In certain embodiments in which cleavage depends on the binding of twozinc finger domain/cleavage half-domain fusion molecules to separatetarget sites, the two target sites can be on opposite. DNA strands(Example 1). In other embodiments, both target sites are on the same DNAstrand.

DNA Binding Domains

Any DNA-binding domain can be used in the methods disclosed herein. Incertain embodiments, the DNA binding domain comprises a zinc fingerprotein. A zinc finger binding domain comprises one or more zincfingers. Miller et al. (1985) EMBO J. 4:1609-1614; Rhodes (1993)Scientific American Feb.:56-65; U.S. Pat. No. 6,453,242. The zinc fingerbinding domains described herein generally include 2, 3, 4, 5, 6 or evenmore zinc fingers.

Typically, a single zinc finger domain is about 30 amino acids inlength. Structural studies have demonstrated that each zinc fingerdomain (motif) contains two beta sheets (held in a beta turn whichcontains the two invariant cysteine residues) and an alpha helix(containing the two invariant histidine residues), which are held in aparticular conformation through coordination of a zinc atom by the twocysteines and the two histidines.

Zinc fingers include both canonical C₂H₂ zinc fingers (i.e., those inwhich the zinc ion is coordinated by two cysteine and two histidineresidues) and non-canonical zinc fingers such as, for example, C₃H zincfingers (those in which the zinc ion is coordinated by three cysteineresidues and one histidine residue) and C₄ zinc fingers (those in whichthe zinc ion is coordinated by four cysteine residues). See also WO02/057293.

Zinc finger binding domains can be engineered to bind to a target site(see above) using standard techniques. See, Example 1; co-owned U.S.Pat. Nos. 6,453,242 and 6,534,261, including references cited therein.An engineered zinc finger binding domain can have a novel bindingspecificity, compared to a naturally-occurring zinc finger protein.Engineering methods include, but are not limited to, rational design andvarious types of selection. Rational design includes, for example, usingdatabases comprising triplet (or quadruplet) nucleotide sequences andindividual zinc finger amino acid sequences, in which each triplet orquadruplet nucleotide sequence is associated with one or more amino acidsequences of zinc fingers which bind the particular triplet orquadruplet sequence.

Exemplary selection methods, including phage display and two-hybridsystems, are disclosed in U.S. Pat. Nos. 5,789,538; 5,925,523;6,007,988; 6,013,453; 6,410,248; 6,140,466; 6,200,759; and 6,242,568; aswell as WO 98/37186; WO 98/53057; WO 00/27878; WO 01/88197 and GB2,338,237.

Enhancement of binding specificity for zinc finger binding domains hasbeen described, for example, in co-owned WO 02/077227.

Since an individual zinc finger binds to a three-nucleotide (i.e.,triplet) sequence (or a four-nucleotide sequence which can overlap, byone nucleotide, with the four-nucleotide binding site of an adjacentzinc finger), the length of a sequence to which a zinc finger bindingdomain is engineered to bind (e.g., a target sequence) will determinethe number of zinc fingers in an engineered zinc finger binding domain.For example, for ZFPs in which the finger motifs do not bind tooverlapping subsites, a six-nucleotide target sequence is bound by atwo-finger binding domain; a nine-nucleotide target sequence is bound bya three-finger binding domain, etc. As noted herein, binding sites forindividual zinc fingers (i.e., subsites) in a target site need not becontiguous, but can be separated by one or several nucleotides,depending on the length and nature of the amino acids sequences betweenthe zinc fingers (i.e., the inter-finger linkers) in a multi-fingerbinding domain.

In a multi-finger zinc finger binding domain, adjacent zinc fingers canbe separated by amino acid linker sequences of approximately 5 aminoacids (so-called “canonical” inter-finger linkers) or, alternatively, byone or more non-canonical linkers. See, e.g., co-owned U.S. Pat. Nos.6,453,242 and 6,534,261. For engineered zinc finger binding domainscomprising more than three fingers, insertion of longer(“non-canonical”) inter-finger linkers between certain of the zincfingers may be preferred as it may increase the affinity and/orspecificity of binding by the binding domain. See, for example, U.S.Pat. No. 6,479,626 and WO 01/53480. Accordingly, multi-finger zincfinger binding domains can also be characterized with respect to thepresence and location of non-canonical inter-finger linkers. Forexample, a six-finger zinc finger binding domain comprising threefingers (joined by two canonical inter-finger linkers), a long linkerand three additional fingers (joined by two canonical inter-fingerlinkers) is denoted a 2×3 configuration. Similarly, a binding domaincomprising two fingers (with a canonical linker therebetween), a longlinker and two additional fingers (joined by a canonical linker) isdenoted a 2×2 protein. A protein comprising three two-finger units (ineach of which the two fingers are joined by a canonical linker), and inwhich each two-finger unit is joined to the adjacent two finger unit bya long linker, is referred to as a 3×2 protein.

The presence of a long or non-canonical inter-finger linker between twoadjacent zinc fingers in a multi-finger binding domain often allows thetwo fingers to bind to subsites which are not immediately contiguous inthe target sequence. Accordingly, there can be gaps of one or morenucleotides between subsites in a target site; i.e., a target site cancontain one or more nucleotides that are not contacted by a zinc finger.For example, a 2×2 zinc finger binding domain can bind to twosix-nucleotide sequences separated by one nucleotide, i.e., it binds toa 13-nucleotide target site. See also Moore et al. (2001a) Proc. Natl.Acad. Sci. USA 98:1432-1436; Moore et al. (2001b) Proc. Natl. Acad. Sci.USA 98:1437-1441 and WO 01/53480.

As mentioned previously, a target subsite is a three- or four-nucleotidesequence that is bound by a single zinc finger. For certain purposes, atwo-finger unit is denoted a binding module. A binding module can beobtained by, for example, selecting for two adjacent fingers in thecontext of a multi-finger protein (generally three fingers) which bind aparticular six-nucleotide target sequence. Alternatively, modules can beconstructed by assembly of individual zinc fingers. See also WO 98/53057and WO 01/53480.

Alternatively, the DNA-binding domain may be derived from a nuclease.For example, the recognition sequences of homing endonucleases andmeganucleases such as I-SceI, I-CeuI, PI-PspI, PI-Sce, I-SceIV, I-CsmI,I-PanI, I-SceII, I-PpoI, I-SceIII, I-CreI, I-TevI, I-TevII and I-TevIIIare known. See also U.S. Pat. No. 5,420,032; U.S. Pat. No. 6,833,252;Belfort et al. (1997) Nucleic Acids Res. 25:3379-338.8; Dujon et al.(1989) Gene 82:115-118; Perler et al. (1994) Nucleic Acids Res. 22,1125-1127; Jasin (1996) Trends Genet. 12:224-228; Gimble et al. (1996)J. Mol. Biol. 263:163-180; Argast et al. (1998) J. Mol. Biol.280:345-353 and the New England Biolabs catalogue. In addition, theDNA-binding specificity of homing endonucleases and meganucleases can beengineered to bind non-natural target sites. See, for example, Chevalieret al. (2002) Molec. Cell 10:895-905; Epinat et al. (2003) Nucleic AcidsRes. 31:2952-2962; Ashworth et al. (2006) Nature 441:656-659; Paques etal. (2007) Current Gene Therapy 7:49-66; U.S. Patent Publication No.20070117128.

Cleavage Domains

The cleavage domain portion of the fusion proteins disclosed herein canbe obtained from any endonuclease or exonuclease. Exemplaryendonucleases from which a cleavage domain can be derived include, butare not limited to, restriction endonucleases and homing endonucleases.See, for example, 2002-2003 Catalogue, New England Biolabs, Beverly,Mass.; and Belfort et al. (1997) Nucleic Acids Res. 25:3379-3388.Additional enzymes which cleave DNA are known (e.g., S1 Nuclease; mungbean nuclease; pancreatic DNase I; micrococcal nuclease; yeast HOendonuclease; see also Linn et al. (eds.) Nucleases, Cold Spring HarborLaboratory Press, 1993). Non limiting examples of homing endonucleasesand meganucleases include I-SceI, I-CeuI, PI-PspI, PI-Sce, I-SceIV,I-CsmI, I-PanI, I-SceII, I-PpoI, I-SceIII, I-CreI, I-TevI, I-TevII andI-TevII are known. See also U.S. Pat. No. 5,420,032; U.S. Pat. No.6,833,252; Belfort et al. (1997) Nucleic Acids Res. 25:3379-3388; Dujonet al. (1989) Gene 82:115-118; Perler et al. (1994) Nucleic Acids Res.22, 1125-1127; Jasin (1996) Trends Genet. 12:224-228; Gimble et al.(1996) J. Mol. Biol. 263:163-180; Argast et al. (1998) J. Mol. Biol.280:345-353 and the New England Biolabs catalogue. One or more of theseenzymes (or functional fragments thereof) can be used as a source ofcleavage domains and cleavage half-domains.

Restriction endonucleases (restriction enzymes) are present in manyspecies and are capable of sequence-specific binding to DNA (at arecognition site), and cleaving DNA at or near the site of binding.Certain restriction enzymes (e.g., Type IIS) cleave DNA at sites removedfrom the recognition site and have separable binding and cleavagedomains. For example, the Type IIS enzyme Fok I catalyzesdouble-stranded cleavage of DNA, at 9 nucleotides from its recognitionsite on one strand and 13 nucleotides from its recognition site on theother. See, for example, U.S. Pat. Nos. 5,356,802; 5,436,150 and5,487,994; as well as Li et al. (1992) Proc. Natl. Acad. Sci. USA89:4275-4279; Li et al. (1993) Proc. Natl. Acad. Sci. USA 90:2764-2768;Kim et al. (1994a) Proc. Natl. Acad. Sci. USA 91:883-887; Kim et al.(1994b) J. Biol. Chem. 269:31,978-31,982. Thus, in one embodiment,fusion proteins comprise the cleavage domain (or cleavage half-domain)from at least one Type IS restriction enzyme and one or more zinc fingerbinding domains, which may or may not be engineered.

An exemplary Type IIS restriction enzyme, whose cleavage domain isseparable from the binding domain, is Fok I. This particular enzyme isactive as a dimer. Bitinaite et al. (1998) Proc. Natl. Acad. Sci. USA95: 10,570-10,575. Accordingly, for the purposes of the presentdisclosure, the portion of the Fok I enzyme used in the disclosed fusionproteins is considered a cleavage half-domain. Thus, for targeteddouble-stranded cleavage and/or targeted replacement of cellularsequences using zinc finger-Fok I fusions, two fusion proteins, eachcomprising a FokI cleavage half-domain, can be used to reconstitute acatalytically active cleavage domain. Alternatively, a singlepolypeptide molecule containing a zinc finger binding domain and two FokI cleavage half-domains can also be used. Parameters for targetedcleavage and targeted sequence alteration using zinc finger-Fok Ifusions are provided elsewhere in this disclosure.

A cleavage domain or cleavage half-domain can be any portion of aprotein that retains cleavage activity, or that retains the ability tomultimerize (e.g., dimerize) to form a functional cleavage domain.

Exemplary Type IIS restriction enzymes are described in co-ownedInternational Publication WO 2007/014275, incorporated by referenceherein in its entirety.

To enhance cleavage specificity, cleavage domains may also be modified.In certain embodiments, variants of the cleavage half-domain areemployed, which variants that minimize or prevent homodimerization ofthe cleavage half-domains. Non-limiting examples of such modifiedcleavage half-domains are described in detail in WO 2007/014275,incorporated by reference in its entirety herein. See, also, Examples.In certain embodiments, the cleavage domain comprises an engineeredcleavage half-domain (also referred to as dimerization domain mutants)that minimize or prevent homodimerization are known to those of skillthe art and described for example in U.S. Patent Publication Nos.20050064474 and 20060188987, incorporated by reference in theirentireties herein. Amino acid residues at positions 446, 447, 479, 483,484, 486, 487, 490, 491, 496, 498, 499, 500, 531, 534, 537, and 538 ofFok I are all targets for influencing dimerization of the Fok I cleavagehalf-domains.

Additional engineered cleavage half-domains of Fok I form an obligateheterodimers can also be used in the ZFNs described herein. The firstcleavage half-domain includes mutations at amino acid residues atpositions 490 and 538 of Fok I and the second cleavage half-domainincludes mutations at amino acid residues 486 and 499.

In certain embodiments, the cleavage domain comprises two cleavagehalf-domains, both of which are part of a single polypeptide comprisinga binding domain, a first cleavage half-domain and a second cleavagehalf-domain. The cleavage half-domains can have the same amino acidsequence or different amino acid sequences, so long as they function tocleave the DNA.

In general, two fusion proteins are required for cleavage if the fusionproteins comprise cleavage half-domains. Alternatively, a single proteincomprising two cleavage half-domains can be used. The two cleavagehalf-domains can be derived from the same endonuclease (or functionalfragments thereof), or each cleavage half-domain can be derived from adifferent endonuclease (or functional fragments thereof). In yet anotherembodiment, two cleavage half-domains are used wherein one of the halfdomains is enzymatically inactive, such that a single-stranded nick isintroduced at the target site (see for example co-owned U.S. provisionalapplication 61/189,800). In addition, the target sites for the twofusion proteins are preferably disposed, with respect to each other,such that binding of the two fusion proteins to their respective targetsites places the cleavage half-domains in a spatial orientation to eachother that allows the cleavage half-domains to form a functionalcleavage domain, e.g., by dimerizing. Thus, in certain embodiments, thenear edges of the target sites are separated by 5-8 nucleotides or by15-18 nucleotides. However any integral number of nucleotides ornucleotide pairs can intervene between two target sites (e.g., from 2 to50 nucleotides or more). In general, the point of cleavage lies betweenthe target sites.

DNA-binding Domain-cleavage Domain Fusions

Methods for design and construction of fusion proteins (andpolynucleotides encoding same) are known to those of skill in the art.For example, methods for the design and construction of fusion proteincomprising zinc finger proteins (and polynucleotides encoding same) aredescribed in co-owned U.S. Pat. Nos. 6,453,242 and 6,534,261; andInternational Publication WO 2007/014275. In certain embodiments,polynucleotides encoding such fusion proteins are constructed. Thesepolynucleotides can be inserted into a vector and the vector can beintroduced into a cell (see below for additional disclosure regardingvectors and methods for introducing polynucleotides into cells).

In certain embodiments of the methods described herein, a fusion proteincomprises a zinc finger binding domain and a cleavage half-domain fromthe Fok I restriction enzyme, and two such fusion proteins are expressedin a cell. Expression of two fusion proteins in a cell can result fromdelivery of the two proteins to the cell; delivery of one protein andone nucleic acid encoding one of the proteins to the cell; delivery oftwo nucleic acids, each encoding one of the proteins, to the cell; or bydelivery of a single nucleic acid, encoding both proteins, to the cell.In additional embodiments, a fusion protein comprises a singlepolypeptide chain comprising two cleavage half domains and a zinc fingerbinding domain. In this case, a single fusion protein is expressed in acell and, without wishing to be bound by theory, is believed to cleaveDNA as a result of formation of an intramolecular dimer of the cleavagehalf-domains.

Two fusion proteins, each comprising a zinc finger binding domain and acleavage half-domain, may be expressed in a cell, and bind to targetsites which are juxtaposed in such a way that a functional cleavagedomain is reconstituted and DNA is cleaved in the vicinity of the targetsites. In one embodiment, cleavage occurs between the target sites ofthe two zinc finger binding domains. One or both of the zinc fingerbinding domains and/or cleavage domains can be engineered.

The components of the fusion proteins (e.g., ZFP-Fok I fusions) may bearranged such that the zinc finger domain is nearest the amino terminusof the fusion protein, and the cleavage half-domain is nearest thecarboxy-terminus. Dimerization of the cleavage half-domains to form afunctional nuclease is brought about by binding of the fusion proteinsto sites on opposite DNA strands, with the 5′ ends of the binding sitesbeing proximal to each other.

Alternatively, the components of the fusion proteins (e.g., ZFP-Fok Ifusions) may be arranged such that the cleavage half-domain is nearestthe amino terminus of the fusion protein, and the zinc finger domain isnearest the carboxy-terminus. In these embodiments, dimerization of thecleavage half-domains to form a functional nuclease is brought about bybinding of the fusion proteins to sites on opposite DNA strands, withthe 3′ ends of the binding sites being proximal to each other.

In yet additional embodiments, a first fusion protein contains thecleavage half-domain nearest the amino terminus of the fusion protein,and the zinc finger domain nearest the carboxy-terminus, and a secondfusion protein is arranged such that the zinc finger domain is nearestthe amino terminus of the fusion protein, and the cleavage half-domainis nearest the carboxy-terminus. In these embodiments, both fusionproteins bind to the same DNA strand, with the binding site of the firstfusion protein containing the zinc finger domain nearest the carboxyterminus located to the 5′ side of the binding site of the second fusionprotein containing the zinc finger domain nearest the amino terminus.

The two fusion proteins can bind in the region of interest in the sameor opposite polarity, and their binding sites (i.e., target sites) canbe separated by any number of nucleotides, e.g., from 0 to 200nucleotides or any integral value therebetween. In certain embodiments,the binding sites for two fusion proteins, each comprising a zinc fingerbinding domain and a cleavage half-domain, can be located between 5 and18 nucleotides apart, for example, 5-8 nucleotides apart, or 15-18nucleotides apart, or 6 nucleotides apart, or 16 nucleotides apart, asmeasured from the edge of each binding site nearest the other bindingsite, and cleavage occurs between the binding sites.

The site at which the DNA is cleaved generally lies between the bindingsites for the two fusion proteins. Double-strand breakage of DNA oftenresults from two single-strand breaks, or “nicks,” offset by 1, 2, 3, 4,5, 6 or more nucleotides, (for example, cleavage of double-stranded DNAby native Fok I results from single-strand breaks offset by 4nucleotides). Thus, cleavage does not necessarily occur at exactlyopposite sites on each DNA strand. In addition, the structure of thefusion proteins and the distance between the target sites can influencewhether cleavage occurs adjacent a single nucleotide pair, or whethercleavage occurs at several sites. However, for targeted integration,cleavage within a range of nucleotides is generally sufficient, andcleavage between particular base pairs is not required.

In the disclosed fusion proteins, the amino acid sequence between thezinc finger domain and the cleavage domain (or cleavage half-domain) isdenoted the “ZC linker.” The ZC linker is to be distinguished from theinter-finger linkers discussed above. ZC linkers are described indetail, for example, in WO 2007/014275.

As discussed in detail below, the fusion protein (ZFN), or apolynucleotide encoding same, is introduced into a cell. Once introducedinto, or expressed in, the cell, the fusion protein binds to the targetsequence in PPP1R12C and cleaves within this gene locus.

Targeted Integration

The disclosed methods and compositions can be used to cleave DNA incellular chromatin, which facilitates targeted integration of anexogenous sequence (donor polynucleotide) as described herein. By“integration” is meant both physical insertion (e.g., into the genome ofa host cell) and, in addition, integration by copying of the donorsequence into the host cell genome via the nucleic acid replicationprocesses.

For targeted integration, one or more zinc finger binding domains areengineered to bind a target site at or near the predetermined cleavagesite, and a fusion protein comprising the engineered zinc finger bindingdomain and a cleavage domain is expressed in a cell. Upon binding of thezinc finger portion of the fusion protein to the target site, the DNA iscleaved, preferably via a double stranded break, near the target site bythe cleavage domain. The presence of a double-stranded break facilitatesintegration of exogenous sequences as described herein via homologousrecombination.

Targeted integration of exogenous sequences, as disclosed herein, can beused to generate cells and cell lines for protein expression. See, forexample, co-owned U.S. Patent Application Publication No. 2006/0063231(the disclosure of which is hereby incorporated by reference herein, inits entirety, for all purposes). For optimal expression of one or moreproteins encoded by exogenous sequences integrated into a genome, thechromosomal integration site should be compatible with high-leveltranscription of the integrated sequences, preferably in a wide range ofcell types and developmental states. However, it has been observed thattranscription of integrated sequences varies depending on theintegration site due to, among other things, the chromatin structure ofthe genome at the integration site. Accordingly, genomic target sitesthat support high-level transcription of integrated sequences aredesirable. In certain embodiments, it will also be desirable thatintegration of exogenous sequences not result in ectopic activation ofone or more cellular genes (e.g., oncogenes). On the other hand, in thecase of integration of promoter and/or enhancer sequences, ectopicexpression may be desired.

The exogenous (donor) sequence can be introduced into the cell prior to,concurrently with, or subsequent to, expression of the fusionprotein(s).

Methods and compositions are also provided that may enhance levels oftargeted recombination including, but not limited to, the use ofadditional ZFP-functional domain fusions. See, WO 2007/014275.

Further increases in efficiency of targeted recombination, in cellscomprising a zinc finger/nuclease fusion molecule and a donor DNAmolecule, are achieved by blocking the cells in the G₂ phase of the cellcycle, when homology-driven repair processes are maximally active. Sucharrest can be achieved in a number of ways. For example, cells can betreated with e.g., drugs, compounds and/or small molecules whichinfluence cell-cycle progression so as to arrest cells in G₂ phase.Exemplary molecules of this type include, but are not limited to,compounds which affect microtubule polymerization (e.g., vinblastine,nocodazole, Taxol), compounds that interact with DNA (e.g.,cis-platinum(II) diamine dichloride, Cisplatin, doxorubicin) and/orcompounds that affect DNA synthesis (e.g., thymidine, hydroxyurea,L-mimosine, etoposide, 5-fluorouracil). Additional increases inrecombination efficiency are achieved by the use of histone deacetylase(HDAC) inhibitors (e.g., sodium butyrate, trichostatin A) which alterchromatin structure to make genomic DNA more accessible to the cellularrecombination machinery.

Additional methods for cell-cycle arrest include overexpression ofproteins which inhibit the activity of the CDK cell-cycle kinases, forexample, by introducing a cDNA encoding the protein into the cell or byintroducing into the cell an engineered ZFP which activates expressionof the gene encoding the protein. Cell-cycle arrest is also achieved byinhibiting the activity of cyclins and CDKs, for example, using RNAimethods (e.g., U.S. Pat. No. 6,506,559) or by introducing into the cellan engineered ZFP which represses expression of one or more genesinvolved in cell-cycle progression such as, for example, cyclin and/orCDK genes. See, e.g., co-owned U.S. Pat. No. 6,534,261 for methods forthe synthesis of engineered zinc finger proteins for regulation of geneexpression.

Alternatively, in certain cases, targeted cleavage is conducted in theabsence of a donor polynucleotide (preferably in S or G₂ phase), andrecombination occurs between homologous chromosomes.

Delivery

The nucleic acids as described herein (e.g., a polynucleotide encodingZFN and/or donor sequence) may be introduced into a cell using anysuitable method.

For plant cells, DNA constructs may be introduced into (e.g., into thegenome of) a desired plant host by a variety of conventional techniques.For reviews of such techniques see, for example, Weissbach & WeissbachMethods for Plant Molecular Biology (1988, Academic Press, N.Y.) SectionVIII, pp. 421-463; and Grierson & Corey, Plant Molecular Biology (1988,2d Ed.), Blackie, London, Ch. 7-9.

For example, the DNA construct may be introduced directly into thegenomic DNA of the plant cell using techniques such as electroporationand microinjection of plant cell protoplasts, or the DNA constructs canbe introduced directly to plant tissue using biolistic methods, such asDNA particle bombardment (see, e.g., Klein et al (1987) Nature327:70-73). Alternatively, the DNA constructs may be combined withsuitable T-DNA flanking regions and introduced into a conventionalAgrobacterium tumefaciens host vector. Agrobacteriumtumefaciens-mediated transformation techniques, including disarming anduse of binary vectors, are well described in the scientific literature.See, for example Horsch et al (1984) Science 233:496-498, and Fraley etal (1983) Proc. Nat'l. Acad. Sci. USA 80:4803.

In addition, gene transfer may be achieved using non-Agrobacteriumbacteria or viruses such as Rhizobium sp. NGR234, Sinorhizoboiummeliloti, Mesorhizobium loti, potato virus X, cauliflower mosaic virusand cassaya vein mosaic virus and/or tobacco mosaic virus, See, e.g.,Chung et al. (2006) Trends Plant Sci. 11(1):1-4.

The virulence functions of the Agrobacterium tumefaciens host willdirect the insertion of the construct and adjacent marker into the plantcell DNA when the cell is infected by the bacteria using binary T DNAvector (Bevan (1984) Nuc. Acid Res. 12:8711-8721) or the co-cultivationprocedure (Horsch et al (1985) Science 227:1229-1231). Generally, theAgrobacterium transformation system is used to engineer dicotyledonousplants (Bevan et al (1982) Ann. Rev. Genet 16:357-384; Rogers et al(1986) Methods Enzymol. 118:627-641). The Agrobacterium transformationsystem may also be used to transform, as well as transfer, DNA tomonocotyledonous plants and plant cells. See U.S. Pat. No. 5,591,616;Hemalsteen et al (1984) EMBO J 3:3039-3041; Hooykass-Van Slogteren et al(1984) Nature 311:763-764; Grimsley et al (1987) Nature 325:1677-179;Boulton et al (1989) Plant Mol. Biol. 12:31-40.; and Gould et al (1991)Plant Physiol. 95:426-434.

Alternative gene transfer and transformation methods include, but arenot limited to, protoplast transformation through calcium-, polyethyleneglycol (PEG)- or electroporation-mediated uptake of naked DNA (seePaszkowski et al. (1984) EMBO J 3:2717-2722, Potrykus et al. (1985)Molec. Gen. Genet. 199:169-177; Fromm et al. (1985) Proc. Nat. Acad.Sci. USA 82:5824-5828; and Shimamoto (1989) Nature 338:274-276) andelectroporation of plant tissues (D'Halluin et al. (1992) Plant Cell4:1495-1505). Additional methods for plant cell transformation includemicroinjection, silicon carbide mediated DNA uptake (Kaeppler et al.(1990) Plant Cell Reporter 9:415-418), and microprojectile bombardment(see Klein et al. (1988) Proc. Nat. Acad. Sci. USA 85:4305-4309; andGordon-Kamm et al. (1990) Plant Cell 2:603-618).

Similarly, the fusion protein(s) (ZFNs) can be introduced aspolypeptides and/or polynucleotides. For example, two polynucleotides,each comprising sequences encoding one of the aforementionedpolypeptides, can be introduced into a cell, and when the polypeptidesare expressed and each binds to its target sequence, cleavage occurs ator near the target sequence. Alternatively, a single polynucleotidecomprising sequences encoding both fusion polypeptides is introducedinto a cell. Polynucleotides can be DNA, RNA or any modified forms oranalogues or DNA and/or RNA.

In certain embodiments, one or more ZFPs or ZFP fusion proteins can becloned into a vector for transformation into prokaryotic or eukaryoticcells for replication and/or expression. Vectors can be prokaryoticvectors, e.g., plasmids, or shuttle vectors, insect vectors, oreukaryotic vectors. A nucleic acid encoding sequences described herein(ZFNs) can also be cloned into an expression vector, for administrationto a plant cell, animal cell, preferably a mammalian cell or a humancell, fungal cell, bacterial cell, or protozoal cell using standardtechniques described for example in Sambrook et al., supra and UnitedStates Patent Publications 20030232410; 20050208489; 20050026157;20050064474; and 20060188987, and International Publication WO2007/014275.

In certain embodiments, the ZFNs and donor sequences are delivered invivo or ex vivo for gene therapy uses. Non-viral vector delivery systemsfor delivering polynucleotides to cells include DNA plasmids, nakednucleic acid, and nucleic acid complexed with a delivery vehicle such asa liposome or poloxamer. Viral vector delivery systems for delivery ofthe ZFNs include DNA and RNA viruses, which have either episomal orintegrated genomes after delivery to the cell. For a review of genetherapy procedures, see Anderson, Science 256:808-813 (1992); Nabel &Felgner, TIBTECH 11:211-217 (1993); Mitani & Caskey, TIBTECH 11:162-166(1993); Dillon, TIBTECH 11: 167-175 (1993); Miller, Nature 357:455-460(1992); Van Brunt, Biotechnology 6(10): 1149-1154 (1988); Vigne,Restorative Neurology and Neuroscience 8:35-36 (1995); Kremer &Perricaudet, British Medical Bulletin 51(1):31-44 (1995); Haddada etal., in Current Topics in Microbiology and Immunology Doerfler and Bohm(eds.) (1995); and Yu et al., Gene Therapy 1:13-26 (1994).

Methods of non-viral delivery of nucleic acids in vivo or ex vivoinclude electroporation, lipofection (see, U.S. Pat. Nos. 5,049,386;4,946,787 and commercially available reagents such as Transfectam™ andLipofectin™), microinjection, biolistics, virosomes, liposomes (see,e.g., Crystal, Science 270:404-410 (1995); Blaese et al. Cancer GeneTher. 2:291-297 (1995); Behr et al., Bioconjugate Chem. 5:382-389(1994); Remy et al., Bioconjugate Chem. 5:647-654 (1994); Gao et al.,Gene Therapy 2:710-722 (1995); Ahmad et al., Cancer Res. 52:4817-4820(1992); U.S. Pat. Nos. 4,186,183, 4,217,344, 4,235,871, 4,261,975,4,485,054, 4,501,728, 4,774,085, 4,837,028, and 4,946,787),immunoliposomes, polycation or lipid:nucleic acid conjugates, naked DNA,artificial virions, viral vector systems (e.g., retroviral, lentivirus,adenoviral, adeno-associated, vaccinia and herpes simplex virus vectorsas described in WO 2007/014275 for delivering proteins comprising ZFPs)and agent-enhanced uptake of DNA. Sonoporation using, e.g., the Sonitron2000 system (Rich-Mar) can also be used for delivery of nucleic acids.

Additional exemplary nucleic acid delivery systems include thoseprovided by Amaxa Biosystems (Cologne, Germany), Maxcyte, Inc.(Rockville, Md.) and BTX Molecular Delivery Systems (Holliston, Mass.).

In certain embodiments, for example, in which transient expression of aZFP fusion protein is preferred, adenoviral based systems can be used.Adenoviral based vectors are capable of very high transductionefficiency in many cell types and do not require cell division. Withsuch vectors, high titer and high levels of expression have beenobtained. This vector can be produced in large quantities in arelatively simple system. Adeno-associated virus (“AAV”) vectors arealso used to transduce cells with target nucleic acids, e.g., in the invitro production of nucleic acids and peptides, and for in vivo and exvivo gene therapy procedures (see, e.g., West et al., Virology 160:38-47(1987); U.S. Pat. No. 4,797,368; WO 93/24641; Kotin, Human Gene Therapy5:793-801 (1994); Muzyczka, J. Clin. Invest. 94:1351 (1994).Construction of recombinant AAV vectors are described in a number ofpublications, including U.S. Pat. No. 5,173,414; Tratschin et al., Mol.Cell. Biol. 5:3251-3260 (1985); Tratschin, et al., Mol. Cell. Biol.4:2072-2081 (1984); Hermonat & Muzyczka, PNAS 81:6466-6470 (1984); andSamulski et al., J. Virol. 63:03822-3828 (1989).

At least six viral vector approaches are currently available for genetransfer in clinical trials, which utilize approaches that involvecomplementation of defective vectors by genes inserted into helper celllines to generate the transducing agent.

pLASN and MFG-S are examples of retroviral vectors that have been usedin clinical trials (Dunbar et al., Blood 85:3048-305 (1995); Kohn etal., Nat. Med. 1:1017-102 (1995); Malech et al., PNAS 94:22 12133-12138(1997)). PA317/pLASN was the first therapeutic vector used in a genetherapy trial. (Blaese et al., Science 270:475-480 (1995)). Transductionefficiencies of 50% or greater have been observed for MFG-S packagedvectors. (Ellem et al., Immunol Immunother. 44(1):10-20 (1997); Dranoffet al., Hum. Gene Ther. 1:111-2 (1997).

Recombinant adeno-associated virus vectors (rAAV) are a promisingalternative gene delivery systems based on the defective andnonpathogenic parvovirus adeno-associated type 2 virus. All vectors arederived from a plasmid that retains only the AAV 145 bp invertedterminal repeats flanking the transgene expression cassette. Efficientgene transfer and stable transgene delivery due to integration into thegenomes of the transduced cell are key features for this vector system.(Wagner et al.; Lancet 351:9117 1702-3 (1998), Kearns et al., Gene Ther.9:748-55 (1996)).

Replication-deficient recombinant adenoviral vectors (Ad) can beproduced at high titer and readily infect a number of different celltypes. Most adenovirus vectors are engineered such that a transgenereplaces the Ad E1a, E1b, and/or E3 genes; subsequently the replicationdefective vector is propagated in human 293 cells that supply deletedgene function in trans. Ad vectors can transduce multiple types oftissues in vivo, including nondividing, differentiated cells such asthose found in liver, kidney and muscle. Conventional Ad vectors have alarge carrying capacity. An example of the use of an Ad vector in aclinical trial involved polynucleotide therapy for antitumorimmunization with intramuscular injection (Sterman et al., Hum. GeneTher. 7:1083-9 (1998)). Additional examples of the use of adenovirusvectors for gene transfer in clinical trials include Rosenecker et al.,Infection 24:1 5-10 (1996); Sterman et al. Hum. Gene Ther. 9:7 1083-1089(1998); Welsh et al., Hum. Gene Ther. 2:205-18 (1995); Alvarez et al.,Hum. Gene Ther. 5:597-613 (1997); Topf et al., Gene Ther. 5:507-513(1998); Sterman et al., Hum. Gene Ther. 7:1083-1089 (1998).

Packaging cells are used to form virus particles that are capable ofinfecting a host cell. Such cells include 293 cells, which packageadenovirus, and ψ2 cells or PA317 cells, which package retrovirus. Viralvectors used in gene therapy are usually generated by a producer cellline that packages a nucleic acid vector into a viral particle. Thevectors typically contain the minimal viral sequences required forpackaging and subsequent integration into a host (if applicable), otherviral sequences being replaced by an expression cassette encoding theprotein to be expressed. The missing viral functions are supplied intrans by the packaging cell line. For example, AAV vectors used in genetherapy typically only possess inverted terminal repeat (ITR) sequencesfrom the AAV genome which are required for packaging and integrationinto the host genome. Viral DNA is packaged in a cell line, whichcontains a helper plasmid encoding the other AAV genes, namely rep andcap, but lacking ITR sequences. The cell line is also infected withadenovirus as a helper. The helper virus promotes replication of the AAVvector and expression of AAV genes from the helper plasmid. The helperplasmid is not packaged in significant amounts due to a lack of ITRsequences. Contamination with adenovirus can be reduced by, e.g., heattreatment to which adenovirus is more sensitive than AAV.

In many gene therapy applications, it is desirable that thepolynucleotides (e.g., ZFN-encoding sequence) be delivered with a highdegree of specificity to a particular tissue type. Accordingly, a viralvector can be modified to have specificity for a given cell type byexpressing a ligand as a fusion protein with a viral coat protein on theouter surface of the virus. The ligand is chosen to have affinity for areceptor known to be present on the cell type of interest. For example,Han et al., Proc. Natl. Acad. Sci. USA 92:9747-9751 (1995), reportedthat Moloney murine leukemia virus can be modified to express humanheregulin fused to gp70, and the recombinant virus infects certain humanbreast cancer cells expressing human epidermal growth factor receptor.This principle can be extended to other virus-target cell pairs, inwhich the target cell expresses a receptor and the virus expresses afusion protein comprising a ligand for the cell-surface receptor. Forexample, filamentous phage can be engineered to display antibodyfragments (e.g., FAB or Fv) having specific binding affinity forvirtually any chosen cellular receptor. Although the above descriptionapplies primarily to viral vectors, the same principles can be appliedto nonviral vectors. Such vectors can be engineered to contain specificuptake sequences which favor uptake by specific target cells.

Gene therapy vectors can be delivered in vivo by administration to anindividual patient, typically by systemic administration (e.g.,intravenous, intraperitoneal, intramuscular, subdermal, or intracranialinfusion) or topical application, as described below. Alternatively,vectors can be delivered to cells ex vivo, such as cells explanted froman individual patient (e.g., lymphocytes, bone marrow aspirates, tissuebiopsy) or universal donor hematopoietic stem cells, followed byreimplantation of the cells into a patient, usually after selection forcells which have incorporated the vector.

Ex vivo cell transfection for diagnostics, research, or for gene therapy(e.g., via re-infusion of the transfected cells into the host organism)is well known to those of skill in the art. In a preferred embodiment,cells are isolated from the subject organism, transfected with a ZFPnucleic acid (gene or cDNA) and exogenous sequence, and re-infused backinto the subject organism (e.g., patient). Various cell types suitablefor ex vivo transfection are well known to those of skill in the art(see, e.g., Freshney et al., Culture of Animal Cells, A Manual of BasicTechnique (3rd ed. 1994)) and the references cited therein for adiscussion of how to isolate and culture cells from patients).

In one embodiment, stem cells are used in ex vivo procedures for celltransfection and gene therapy. The advantage to using stem cells is thatthey can be differentiated into other cell types in vitro, or can beintroduced into a mammal (such as the donor of the cells) where theywill engraft in the bone marrow. Methods for differentiating CD34+ cellsin vitro into clinically important immune cell types using cytokinessuch a GM-CSF, IFN-γ and TNF-α are known (see Inaba et al., J. Exp. Med.176:1693-1702 (1992)).

Stem cells are isolated for transduction and differentiation using knownmethods. For example, stem cells are isolated from bone marrow cells bypanning the bone marrow cells with antibodies which bind unwanted cells,such as CD4+ and CD8+ (T cells), CD45+ (panb cells), GR-1(granulocytes), and lad (differentiated antigen presenting cells) (seeInaba et al., J. Exp. Med. 176:1693-1702 (1992)).

In one embodiment, the cell to be used is an oocyte.

In other embodiments, cells derived from model organisms may be used.These can include cells derived from xenopus, insect cells (e.g.,drosophilia) and nematode cells.

Vectors (e.g., retroviruses, adenoviruses, liposomes, etc.) comprisingnucleic acids as described herein can also be administered directly toan organism for transduction of cells in vivo. Alternatively, naked DNAcan be administered. Administration is by any of the routes normallyused for introducing a molecule into ultimate contact with blood ortissue cells including, but not limited to, injection, infusion, topicalapplication and electroporation. Suitable methods of administering suchnucleic acids are available and well known to those of skill in the art,and, although more than one route can be used to administer a particularcomposition, a particular route can often provide a more immediate andmore effective reaction than another route.

Methods for introduction of DNA into hematopoietic stem cells aredisclosed, for example, in U.S. Pat. No. 5,928,638. Vectors useful forintroduction of transgenes into hematopoietic stem cells, e.g., CD34⁺cells, include adenovirus Type 35.

Vectors suitable for introduction of transgenes into immune cells (e.g.,T-cells) include non-integrating lentivirus vectors. See, for example,Ory et al. (1996) Proc. Natl. Acad. Sci. USA 93:11382-11388; Dull et al.(1998) J. Virol. 72:8463-8471; Zuffery et al. (1998) J. Virol.72:9873-9880; Follenzi et al. (2000) Nature Genetics 25:217-222.

Pharmaceutically acceptable carriers are determined in part by theparticular composition being administered, as well as by the particularmethod used to administer the composition. Accordingly, there is a widevariety of suitable formulations of pharmaceutical compositionsavailable, as described below (see, e.g., Remington's PharmaceuticalSciences, 17th ed., 1989).

As noted above, one or more of the ZFN fusion proteins can be also beintroduced into the cell as polypeptides using methods described forexample in WO 2007/014275. Non-limiting examples of protein deliveryvehicles include, “membrane translocation polypeptides,” for examplepeptide have amphiphilic or hydrophobic amino acid subsequences thathave the ability to act as membrane-translocating carriers, toxinmolecules, liposomes and liposome derivatives such as immunoliposomes(including targeted liposomes).

ZFPs and expression vectors encoding ZFPs can be administered directlyto the patient for targeted cleavage integration into the PPP1R12C locusfor therapeutic or prophylactic applications, for example, cancer,ischemia, diabetic retinopathy, macular degeneration, rheumatoidarthritis, psoriasis, HIV infection, sickle cell anemia, Alzheimer'sdisease, muscular dystrophy, neurodegenerative diseases, vasculardisease, cystic fibrosis, stroke, and the like.

Administration of therapeutically effective amounts is by any of theroutes normally used for introducing ZFP into ultimate contact with thetissue to be treated. The ZFPs are administered in any suitable manner,preferably with pharmaceutically acceptable carriers. Suitable methodsof administering such modulators are available and well known to thoseof skill in the art, and, although more than one route can be used toadminister a particular composition, a particular route can oftenprovide a more immediate and more effective reaction than another route.

Pharmaceutically acceptable carriers are determined in part by theparticular composition being administered, as well as by the particularmethod used to administer the composition. Accordingly, there is a widevariety of suitable formulations of pharmaceutical compositions that areavailable (see, e.g., Remington's Pharmaceutical Sciences, 17^(th) ed.1985)).

The ZFPs, alone or in combination with other suitable components, can bemade into aerosol formulations (i.e., they can be “nebulized”) to beadministered via inhalation. Aerosol formulations can be placed intopressurized acceptable propellants, such as dichlorodifluoromethane,propane, nitrogen, and the like.

Formulations suitable for parenteral administration, such as, forexample, by intravenous, intramuscular, intradermal, and subcutaneousroutes, include aqueous and non-aqueous, isotonic sterile injectionsolutions, which can contain antioxidants, buffers, bacteriostats, andsolutes that render the formulation isotonic with the blood of theintended recipient, and aqueous and non-aqueous sterile suspensions thatcan include suspending agents, solubilizers, thickening agents,stabilizers, and preservatives. The disclosed compositions can beadministered, for example, by intravenous infusion, orally, topically,intraperitoneally, intravesically or intrathecally. The formulations ofcompounds can be presented in unit-dose or multi-dose sealed containers,such as ampules and vials. Injection solutions and suspensions can beprepared from sterile powders, granules, and tablets of the kindpreviously described.

Transformed plant cells which are produced by any of the above plantcell transformation techniques can be cultured to regenerate a wholeplant which possesses the transformed genotype and thus the desiredphenotype. Such regeneration techniques rely on manipulation of certainphytohormones in a tissue culture growth medium, typically relying on abiocide and/or herbicide marker which has been introduced together withthe desired nucleotide sequences. Plant regeneration from culturedprotoplasts is described in Evans, et al., “Protoplasts Isolation andCulture” in Handbook of Plant Cell Culture, pp. 124-176, MacmillianPublishing Company, New York, 1983; and Binding, Regeneration of Plants,Plant Protoplasts, pp. 21-73, CRC Press, Boca Raton, 1985. Regenerationcan also be obtained from plant callus, explants, organs, pollens,embryos or parts thereof. Such regeneration techniques are describedgenerally in Klee et al (1987) Ann. Rev. of Plant Phys. 38:467-486.

Nucleic acids introduced into a plant cell can be used to confer desiredtraits on essentially any plant. A wide variety of plants and plant cellsystems may be engineered for the desired physiological and agronomiccharacteristics described herein using the nucleic acid constructs ofthe present disclosure and the various transformation methods mentionedabove. In preferred embodiments, target plants and plant cells forengineering include, but are not limited to, those monocotyledonous anddicotyledonous plants, such as crops including grain crops (e.g., wheat,maize, rice, millet, barley), fruit crops (e.g., tomato, apple, pear,strawberry, orange), forage crops (e.g., alfalfa), root vegetable crops(e.g., carrot, potato, sugar beets, yam), leafy vegetable crops (e.g.,lettuce, spinach); flowering plants (e.g., petunia, rose,chrysanthemum), conifers and pine trees (e.g., pine fir, spruce); plantsused in phytoremediation (e.g., heavy metal accumulating plants); oilcrops (e.g., sunflower, rape seed) and plants used for experimentalpurposes (e.g., Arabidopsis). Thus, the disclosed methods andcompositions have use over a broad range of plants, including, but notlimited to, species from the genera Asparagus, Avena, Brassica, Citrus,Citrullus, Capsicum, Cucurbita, Daucus, Erigeron, Glycine, Gossypium,Hordeum, Lactuca, Lolium, Lycopersicon, Malus, Manihot, Nicotiana,Orychophragmus, Oryza, Persea, Phaseolus, Pisum, Pyrus, Prunus,Raphanus, Secale, Solanum, Sorghum, Triticum, Vitis, Vigna, and Zea.

One of skill in the art will recognize that after the expressioncassette is stably incorporated in transgenic plants and confirmed to beoperable, it can be introduced into other plants by sexual crossing. Anyof a number of standard breeding techniques can be used, depending uponthe species to be crossed.

A transformed plant cell, callus, tissue or plant may be identified andisolated by selecting or screening the engineered plant material fortraits encoded by the marker genes present on the transforming DNA. Forinstance, selection may be performed by growing the engineered plantmaterial on media containing an inhibitory amount of the antibiotic orherbicide to which the transforming gene construct confers resistance.Further, transformed plants and plant cells may also be identified byscreening for the activities of any visible marker genes (e.g., theβ-glucuronidase, luciferase, B or C1 genes) that may be present on therecombinant nucleic acid constructs. Such selection and screeningmethodologies are well known to those skilled in the art.

Physical and biochemical methods also may be used to identify plant orplant cell transformants containing inserted gene constructs. Thesemethods include but are not limited to: 1) Southern analysis or PCRamplification for detecting and determining the structure of therecombinant DNA insert; 2) Northern blot, S1 RNase protection,primer-extension or reverse transcriptase-PCR amplification fordetecting and examining RNA transcripts of the gene constructs; 3)enzymatic assays for detecting enzyme or ribozyme activity, where suchgene products are encoded by the gene construct; 4) protein gelelectrophoresis, Western blot techniques, immunoprecipitation, orenzyme-linked immunoassays, where the gene construct products areproteins. Additional techniques, such as in situ hybridization, enzymestaining, and immunostaining, also may be used to detect the presence orexpression of the recombinant construct in specific plant organs andtissues. The methods for doing all these assays are well known to thoseskilled in the art.

The present disclosure also encompasses seeds of the transgenic plantsdescribed above wherein the seed has the transgene or gene construct.The present disclosure further encompasses the progeny, clones, celllines or cells of the transgenic plants described above wherein saidprogeny, clone, cell line or cell has the transgene or gene construct.

EXAMPLES Example 1 Design of Linear Donor Constructs

Linear donor constructs with homology arms of 50, 75 or 100 base pairsflanking a sequence encoding a protein of interest were designed andconstructed as follows. Donor constructs included homology armscontained within the PPP1R12C locus (also referred to as AAVS1 or p84site) or within the endogenous IL2Rγ locus. See, U.S. ProvisionalApplication No. 60/926,322, filed Apr. 26, 2007 for a description of thePPP1R12C locus, incorporated by reference in its entirety herein.

Donor constructs were prepared by PCR using primers with 50, 75 or 100base pairs of homology to the genomic target (PPP1R12C or IL2Rγ). Thetemplates used for these PCRs were plasmid molecules containing two long(approx. 750 bp) fragments homologous to the genomic target, flanking aGFP construct (GFP constructs are elaborated upon in sections 0139 forAAVS1 and 0140 for IL2Rγ). In addition, the primers were constructed toinclude phosphorothioate phosphodiester bonds at the first and secondphosphodiester bonds of the 5′ ends of the primers to protect the lineardonor from exonucleolytic degradation. Phosphorothioate phosphodiesterbonds were introduced using standard techniques, for example asdescribed in Ciafre et al. (1995) Nucleic Acids Res. 23(20):4134-42 andJohansson et al. (2002) Vaccine 20(27-28):3379-88.

Alternatively, donor constructs can be prepared by PCR as shownschematically in FIG. 1. Briefly, the donors can be made by PCR using aprimer with a 50, 75 or 100 base pair 5′ portion homologous to thegenomic target (PPP1R12C or IL2Rγ) and a 15-30 base pair portionidentical to the open reading frame (ORF) of interest. In addition, theprimers can be constructed to include phosphorothioate phosphodiesterbonds at the first and second phosphodiester bonds of the 5′ ends of theprimers to protect the linear donor from exonucleolytic degradation.Phosphorothioate phosphodiester bonds can be introduced using standardtechniques, for example as described in Ciafre et al. (1995) NucleicAcids Res. 23(20):4134-42 and Johansson et al. (2002) Vaccine20(27-28):3379-88.

PCR primers for constructs containing 50, 75 and 100 base pair homologyarms to PPP1R12C are shown in Table 1 and PCR primers for constructscontaining 50 base pair homology arms to IL2Rγ are shown in Table 2.

TABLE 1 SEQ PCR ID primer Sequence NO AAV-GGCTCTGGTTCTGGGTACTTTTATCTGTCCCCTCCACCCCA 5 50F CAGTGGGGC AAV-AGGAGGAGGCCTAAGGATGGGGCTTTTCTGTCACCAATC 6 50R CTGTCCCTAGT AAV-TTATATTCCCAGGGCCGGTTAATGTGGCTCTGGTTCTGGG 7 75FTACTTTTATCTGTCCCCTCCACCCCACAGTGGGGC AAV-TAGACCCAATATCAGGAGACTAGGAAGGAGGAGGCCTAA 8 75RGGATGGGGCTTTTCTGTCACCAATCCTGTCCCTAGT AAV-CCTGTGTCCCCGAGCTGGGACCACCTTATATTCCCAGGGC 9 100FCGGTTAATGTGGCTCTGGTTCTGGGTACTTTTATCTGTCCC CTCCACCCCACAGTGGGGC AAV-AATCTGCCTAACAGGAGGTGGGGGTTAGACCCAATATCA 10 100RGGAGACTAGGAAGGAGGAGGCCTAAGGATGGGGCTTTTC TGTCACCAATCCTGTCCCTAGT

TABLE 2 SEQ PCR ID primer Sequence NO IL-50FGTGTGGATGGGCAGAAACGCTACACGTTTCGTGTTCGGA 11 GCCGCTTTAAC IL-50RTGGATTGGGTGGCTCCATTCACTCCAATGCTGAGCACTT 12 CCACAGAGTGG

Multiple PCR reactions were run for each donor construct. Conditions forboth AAVS1 and IL2Rγ donor PCRs: 95° C., 3 min→30×[95° C., 30 sec; 72°C., 2 min]→72° C., 5 min→4 hold 4° C. The reactions were pooled and theconstructs purified using QiaQuick™ PCR purification kit (Qiagen) toobtain the constructs shown in FIGS. 2 through 5.

FIGS. 2, 3 and 4 show donor molecules targeted to PPP1R12C (AAVS1). Inparticular, FIG. 2 shows a linear donor molecule (SEQ ID NO:1) targetedto AAVS1 and having homology arms of 100 base pairs and referred to asAAVS1 100 bp HA donor. The left homology arm of AAVS1 100 bp HA extendsfrom nucleotides 1 to 100 (lowercase, underlined); an SA site extendsfrom nucleotides 107 to 132 (lowercase, bold); a sequence encoding a 2Apeptide from nucleotides 141 to 212 (uppercase, no underlining); asequence encoding green fluorescent protein (GFP) poly(A) extends fromnucleotides 219 to 1,215 (uppercase, underlined); and a right homologyarm extends from nucleotides 1235 to 1334 (lowercase, underlined).

FIG. 3 shows a linear donor molecule (SEQ ID NO:2) having homology armsof 75 base pairs and designated AAVS1 75 bp HA. In this construct, theleft homology arm extends from nucleotides 1 to 75 (lowercase,underlined); an SA site extends from nucleotides 82 to 107 (lowercase,bold); a sequence encoding a 2A peptide from nucleotides 116 to 187(uppercase, no underlining); a sequence encoding GFP poly(A) extendsfrom nucleotides 194 to 1,190 (uppercase, underlined); and a righthomology arm extends from nucleotides 1210 to 1284 (lowercase,underlined).

FIG. 4 shows a linear donor molecule (SEQ ID NO:3) having homology armsof 50 base pairs and designated AAVS1 50 bp HA. AAVS1 50 bp HA comprisesa left homology arm from nucleotides 1 to 50 (lowercase, underlined); anSA site from nucleotides 57 to 82 (lowercase, bold); a sequence encodinga 2A peptide from nucleotides 91 to 162 (uppercase, no underlining); asequence encoding GFP poly(A) from nucleotides 169 to 1,165 (uppercase,underlined); and a right homology arm from nucleotides 1,185 to 1,234(lowercase, underlined).

The sequence of a donor molecule for IL2Rγ is shown in FIG. 5 (SEQ IDNO:4). This molecule comprises homology arms of 50 base pairs (lefthomology arm from nucleotides 1 to 50 (lowercase, underlined) and righthomology arm from nucleotides 1,639 to 1,688 (lower, underlined)). TheIL2Rγ 50 bp HA donor molecule also comprises an hPGK promoter sequencefrom nucleotides 79 to 594 (lowercase, bold) and a sequence encoding GFPpoly(A) from nucleotides 615 to 1,611 (uppercase, underlined).

Example 2 Targeted Integration of Linear Donor Constructs

To evaluate targeted integration of linear donor constructs having short(50-100 base pair) homology arms, the linear donors and a pair of fusionproteins comprising a zinc finger protein nuclease (ZFNs) as describedin U.S. Provisional Application No. 60/926,322, filed Apr. 26, 2007 andshown in Table 3 (DNA target sites indicated in uppercase letters;non-contacted nucleotides indicated in lowercase), were transfected intoK562 cells using the Amaxa™ Nucleofection kit as shown in Table 4.

TABLE 3 ZFN Name Target Site F1 F2 F3 F4 2189- acTAGGGACAG QSSNLARRPDFLNQ QSGHLAR RSDNLTT 11 GATtg (SEQ ID (SEQ ID (SEQ ID (SEQ ID (SEQ IDNO: NO: 14) NO: 15) NO: 16) NO: 17) 13) r2182- ccCCACTGTGG QSSHLTRRSDHLTT HNYARDC QKATRTT 8 GGTgg (SEQ ID (SEQ ID (SEQ ID (SEQ ID (SEQ IDNO: NO: 19) NO: 20) NO: 21) NO: 22) 18)

TABLE 4 ZFN target Donor con'c Sample # (2.5 μg) Donor (μg) 1 GFP none 2no ZFN SA-2A-GFP-pA (circular) 50 3 no ZFN 50 bp HA donor 5 4 no ZFN 75bp HA donor 5 5 no ZFN 100 bp HA donor 5 6 no ZFN 50 bp HA donor 6.9 7no ZFN 100 bp HA donor 7.5 8 AAVS1 SA-2A-GFP-pA (circular) 50 9 AAVS1 50bp HA donor 5 10 AAVS1 75 bp HA donor 5 11 AAVS1 100 bp HA donor 5 12AAVS1 50 bp HA donor 6.9 13 AAVS1 100 bp HA donor 7.5

The SA-2A-GFP-pA donor refers to the 1,647 bp circular donor fragmentdescribed in U.S. Provisional Application No. 60/926,322, correspondingto positions 60318104-60319750 of PPP1R12C.

Forty eight hours after transfection, the rate of targeted integration(TI) was assayed by a radiolabelled PCR assay and Southern blotting, asdescribed Moehle et al. (2007) Proc. Nat'l Acad. Sci. USA 104:3055-3060.

Results of PCR and Southern blotting are shown in FIG. 6 and FIG. 7,respectively. The top of each lane is marked with the sample number(left column, Table 4) and the percent of chromosomes modified by islisted below each lane.

In addition, one week after transfection, the percentage of GFP-positivecells was assayed by FACS, also as described Moehle et al. (2007).

Results are shown in Table 5 and FIG. 8 and confirm that the GFP ORF ofthe linear donor sequences was integrated into the genome.

TABLE 5 ZFNs (2.5 ug) Donor Amount % GFP MFI Green TI % 1 GFP 0.21 17.990 2 SA-2A-GFP-pA Donor 50 ug 37.28 46.32 0 3 50bp HA Donor 5 ug 2.353.75 0 4 75bp HA Donor 5 ug 0.8 29.24 0 5 100bp HA Donor 5 ug 0.2820.81 0 6 50bp HA Donor 6.9 ug 2.07 12.51 0 7 100bp HA Donor 7.5 ug 0.8112.21 0 8 AAVS1 SA-2A-GFP-pA Donor 50 ug 14.47 18.1 2 9 AAVS1 50bp HADonor 5 ug 13.15 8.71 4 10 AAVS1 75bp HA Donor 5 ug 9.31 7.52 3.1 11AAVS1 100bp HA Donor 5 ug 8.71 8.28 3.9 12 AAVS1 50bp HA Donor 6.9 ug17.48 9.26 9.4 13 AAVS1 100bp HA Donor 7.5 ug 8.91 8.71 4.6

Thus, these results demonstrate that linear donor constructs with shorthomology arms (˜50-100 bp) can be used to efficiently transfer asequence encoding a polypeptide of interest to a specified genomiclocation. The linear donor constructs described herein are rapidlygenerated by PCR using a plasmid template and can be protected fromexonucleolytic degradation using phosphorothioate modification.

All patents, patent applications and publications mentioned herein arehereby incorporated by reference, in their entireties, for all purposes.

Although disclosure has been provided in some detail by way ofillustration and example for the purposes of clarity of understanding,it will be apparent to those skilled in the art that various changes andmodifications can be practiced without departing from the spirit orscope of the disclosure. Accordingly, the foregoing descriptions andexamples should not be construed as limiting.

1. A linear donor nucleic acid molecule comprising homology arms of between 50 and 750 base pairs and a sequence of interest, wherein the homology arms flank the sequence of interest.
 2. The linear donor nucleic acid of claim 1, wherein the homology arms are between 50 and 100 base pairs in length.
 3. The linear donor nucleic acid of claim 1, wherein one or more of the base pairs of the homology arms are joined with a phosphorothioate phosphodiester bond.
 4. The linear donor nucleic acid of claim 3, wherein the phosphorothioate phosphodiester bonds are positioned at the first and, optionally, second bonds of the 5′ and 3′ ends of the donor nucleic acid.
 5. The linear donor nucleic acid of claim 1, further comprising, between the homology arms, a sequence encoding a 2A peptide.
 6. The linear donor nucleic acid of claim 1, further comprising, between the homology arms, a sequence comprising an SA site.
 7. The linear donor nucleic acid of claim 1, further comprising, between the homology arms, a sequence comprising an IRES sequence.
 8. The linear donor nucleic acid of claim 1, wherein the sequence of interest does not encode a polypeptide.
 9. The linear donor nucleic acid of claim 1, further comprising a promoter sequence operably linked to the sequence of interest.
 10. The linear donor nucleic acid of claim 1, wherein the sequence of interest encodes a polypeptide.
 11. The linear donor nucleic acid according to claim 10, wherein the polypeptide is selected from the group consisting of an antibody, an antigen, an enzyme, a growth factor, a cell surface receptor, a nuclear receptor, a hormone, a lymphokine, a cytokine, a reporter gene, a selectable marker, a secreted factor, an epitope tag and functional fragments thereof and combinations thereof.
 12. The linear donor nucleic acid of claim 1, wherein the sequence contains a non-coding nucleic acid.
 13. The linear donor nucleic acid according to claim 12, wherein the non-coding nucleic acid is selected from the group consisting of a miRNA, and SH-RNA, or siRNA.
 14. A method for homology-dependent targeted integration of a sequence of interest into a region of interest in the genome of the cell, the method comprising the steps of: (a) expressing a fusion protein in the cell, the fusion protein comprising a DNA-binding domain and cleavage domain or a cleavage half-domain, wherein the DNA-binding domain has been engineered to bind to a target site in the region of interest; (b) contacting the cell with a donor polynucleotide of claim 1, wherein binding of the fusion protein to the target site cleaves the genome of the cell in the region of the interest, thereby resulting in homology-dependent targeted integration of the sequence of interest into the genome of the cell.
 15. A method for homology-dependent targeted integration of a sequence of interest into a cell, the method comprising: (a) expressing a first fusion protein in the cell, the first fusion protein comprising a first DNA-binding domain and a first cleavage half-domain, wherein the first DNA-binding domain has been engineered to bind to a first target site in a region of interest in the genome of the cell; (b) expressing a second fusion protein in the cell, the second fusion protein comprising a second DNA-domain and a second cleavage half domain, wherein the second zinc finger binding domain binds to a second target site in the region of interest in the genome of the cell, wherein the second target site is different from the first target site; and (c) contacting the cell with a polynucleotide comprising a donor nucleic acid according to claim 1; wherein binding of the first fusion protein to the first target site, and binding of the second fusion protein to the second target site, positions the cleavage half-domains such that the genome of the cell is cleaved in the region of interest, thereby resulting in homology-dependent integration of the donor nucleic said into the genome of the cell.
 16. The method of claim 14, wherein at least one DNA-binding domain is a zinc finger binding domain.
 17. The method of claim 14, wherein at least one DNA-binding domain is a meganuclease DNA-binding domain.
 18. The method of claim 14, wherein the sequence of interest from the integrated donor nucleic acid expresses a polypeptide.
 19. The method of claim 14, wherein the sequence in interest from the integrated donor comprises a non-coding nucleic acid sequence.
 20. The method of claim 14, wherein the cleavage domain is from a meganuclease.
 21. The method of claim 14, wherein the first and second cleavage half-domains are from a Type IIS restriction endonuclease.
 22. The method according to claim 21, wherein the Type IIS restriction endonuclease is selected from the group consisting of FokI and StsI.
 23. The method according to claim 14, wherein the cell is arrested in the G2 phase of the cell cycle.
 24. The method according to claim 14, wherein at least one of the fusion proteins comprises an alteration in the amino acid sequence of the dimerization interface of the cleavage half-domain.
 25. The method according to claim 14, wherein the cell is a mammalian cell.
 26. The method according to claim 14, wherein the cell is a human cell.
 27. The method according to claim 14, wherein the cell is a plant cell. 